Repository: expede/algae Branch: main Commit: 8e9e2487b2d7 Files: 80 Total size: 113.8 KB Directory structure: gitextract_pg39seh_/ ├── .credo.exs ├── .envrc ├── .github/ │ ├── CODE_OF_CONDUCT.md │ ├── PULL_REQUEST_TEMPLATE.md │ └── workflows/ │ ├── ci.yaml │ └── greetings.yml ├── .gitignore ├── .tool-versions ├── LICENSE ├── README.md ├── brand/ │ └── LOGO_LICENSE ├── lib/ │ ├── algae/ │ │ ├── either.ex │ │ ├── free.ex │ │ ├── id/ │ │ │ ├── applicative.ex │ │ │ ├── apply.ex │ │ │ ├── chain.ex │ │ │ ├── comonad.ex │ │ │ ├── extend.ex │ │ │ ├── foldable.ex │ │ │ ├── functor.ex │ │ │ ├── generator.ex │ │ │ ├── monad.ex │ │ │ ├── monoid.ex │ │ │ ├── ord.ex │ │ │ ├── semigroup.ex │ │ │ ├── setoid.ex │ │ │ └── traversable.ex │ │ ├── id.ex │ │ ├── internal/ │ │ │ └── needs_explicit_default_error.ex │ │ ├── internal.ex │ │ ├── maybe.ex │ │ ├── reader/ │ │ │ ├── applicative.ex │ │ │ ├── apply.ex │ │ │ ├── chain.ex │ │ │ ├── functor.ex │ │ │ ├── generator.ex │ │ │ └── monad.ex │ │ ├── reader.ex │ │ ├── state/ │ │ │ ├── applicative.ex │ │ │ ├── apply.ex │ │ │ ├── chain.ex │ │ │ ├── functor.ex │ │ │ ├── generator.ex │ │ │ └── monad.ex │ │ ├── state.ex │ │ ├── tree/ │ │ │ ├── binary_search/ │ │ │ │ ├── applicative.ex │ │ │ │ ├── apply.ex │ │ │ │ ├── chain.ex │ │ │ │ ├── extend.ex │ │ │ │ ├── foldable.ex │ │ │ │ ├── functor.ex │ │ │ │ ├── generator.ex │ │ │ │ ├── monad.ex │ │ │ │ ├── monoid.ex │ │ │ │ ├── ord.ex │ │ │ │ ├── semigroup.ex │ │ │ │ └── setoid.ex │ │ │ ├── binary_search.ex │ │ │ ├── rose/ │ │ │ │ ├── applicative.ex │ │ │ │ ├── apply.ex │ │ │ │ ├── chain.ex │ │ │ │ ├── foldable.ex │ │ │ │ ├── functor.ex │ │ │ │ ├── generator.ex │ │ │ │ └── monad.ex │ │ │ └── rose.ex │ │ ├── writer/ │ │ │ ├── applicative.ex │ │ │ ├── apply.ex │ │ │ ├── chain.ex │ │ │ ├── functor.ex │ │ │ ├── generator.ex │ │ │ └── monad.ex │ │ └── writer.ex │ └── algae.ex ├── mix.exs ├── shell.nix └── test/ ├── algae_dsl_aliasing_test.exs ├── algae_test.exs ├── support/ │ └── example.ex └── test_helper.exs ================================================ FILE CONTENTS ================================================ ================================================ FILE: .credo.exs ================================================ %{ configs: [ %{ name: "default", files: %{ included: ["lib/", "test"], excluded: [] }, checks: [ {Credo.Check.Consistency.TabsOrSpaces}, {Credo.Check.Design.AliasUsage, false}, {Credo.Check.Readability.MaxLineLength, priority: :low, max_length: 100} ] } ] } ================================================ FILE: .envrc ================================================ use nix export MIX_HOME=$(pwd)/.mix export PATH=$PATH:$(pwd)/.mix/escripts ================================================ FILE: .github/CODE_OF_CONDUCT.md ================================================ # Code of Conduct ## 1. Purpose A primary goal of Witchcrafters is to be inclusive to the largest number of contributors, with the most varied and diverse backgrounds possible. As such, we are committed to providing a friendly, safe and welcoming environment for all, regardless of gender, sexual orientation, ability, ethnicity, socioeconomic status, and religion (or lack thereof). This code of conduct outlines our expectations for all those who participate in our community, as well as the consequences for unacceptable behavior. We invite all those who participate in Witchcrafters to help us create safe and positive experiences for everyone. ## 2. Open Source Citizenship A supplemental goal of this Code of Conduct is to increase open source citizenship by encouraging participants to recognize and strengthen the relationships between our actions and their effects on our community. Communities mirror the societies in which they exist and positive action is essential to counteract the many forms of inequality and abuses of power that exist in society. If you see someone who is making an extra effort to ensure our community is welcoming, friendly, and encourages all participants to contribute to the fullest extent, we want to know. ## 3. Expected Behavior The following behaviors are expected and requested of all community members: * Participate in an authentic and active way. In doing so, you contribute to the health and longevity of this community. * Exercise consideration and respect in your speech and actions. * Attempt collaboration before conflict. * Refrain from demeaning, discriminatory, or harassing behavior and speech. * Be mindful of your surroundings and of your fellow participants. Alert community leaders if you notice a dangerous situation, someone in distress, or violations of this Code of Conduct, even if they seem inconsequential. * Remember that community event venues may be shared with members of the public; please be respectful to all patrons of these locations. ## 4. Unacceptable Behavior The following behaviors are considered harassment and are unacceptable within our community: * Violence, threats of violence or violent language directed against another person. * Sexist, racist, homophobic, transphobic, ableist or otherwise discriminatory jokes and language. * Posting or displaying sexually explicit or violent material. * Posting or threatening to post other people’s personally identifying information ("doxing"). * Personal insults, particularly those related to gender, sexual orientation, race, religion, or disability. * Inappropriate photography or recording. * Inappropriate physical contact. You should have someone’s consent before touching them. * Unwelcome sexual attention. This includes, sexualized comments or jokes; inappropriate touching, groping, and unwelcomed sexual advances. * Deliberate intimidation, stalking or following (online or in person). * Advocating for, or encouraging, any of the above behavior. * Sustained disruption of community events, including talks and presentations. ## 5. Consequences of Unacceptable Behavior Unacceptable behavior from any community member, including sponsors and those with decision-making authority, will not be tolerated. Anyone asked to stop unacceptable behavior is expected to comply immediately. If a community member engages in unacceptable behavior, the community organizers may take any action they deem appropriate, up to and including a temporary ban or permanent expulsion from the community without warning (and without refund in the case of a paid event). ## 6. Reporting Guidelines If you are subject to or witness unacceptable behavior, or have any other concerns, please notify a community organizer as soon as possible. hello@brooklynzelenka.com. Additionally, community organizers are available to help community members engage with local law enforcement or to otherwise help those experiencing unacceptable behavior feel safe. In the context of in-person events, organizers will also provide escorts as desired by the person experiencing distress. ## 7. Addressing Grievances If you feel you have been falsely or unfairly accused of violating this Code of Conduct, you should notify the maintainers with a concise description of your grievance. Your grievance will be handled in accordance with our existing governing policies. ## 8. Scope We expect all community participants (contributors, paid or otherwise; sponsors; and other guests) to abide by this Code of Conduct in all community venues–online and in-person–as well as in all one-on-one communications pertaining to community business. This code of conduct and its related procedures also applies to unacceptable behavior occurring outside the scope of community activities when such behavior has the potential to adversely affect the safety and well-being of community members. ## 9. Contact info hello@fission.codes ## 10. License and attribution This Code of Conduct is distributed under a [Creative Commons Attribution-ShareAlike license](http://creativecommons.org/licenses/by-sa/3.0/). Portions of text derived from the [Django Code of Conduct](https://www.djangoproject.com/conduct/) and the [Geek Feminism Anti-Harassment Policy](http://geekfeminism.wikia.com/wiki/Conference_anti-harassment/Policy). Retrieved on November 22, 2016 from [http://citizencodeofconduct.org/](http://citizencodeofconduct.org/) ================================================ FILE: .github/PULL_REQUEST_TEMPLATE.md ================================================ A similar PR may already be submitted! Please search among the [Pull request](../) before creating one. Thanks for submitting a pull request! Please provide enough information so that others can review your pull request: For more information, see the `CONTRIBUTING` guide. ## Summary This PR fixes/implements the following **bugs/features** * [ ] Bug 1 * [ ] Bug 2 * [ ] Feature 1 * [ ] Feature 2 * [ ] Breaking changes Explain the **motivation** for making this change. What existing problem does the pull request solve? ## Test plan (required) Demonstrate the code is solid. Example: The exact commands you ran and their output, screenshots / videos if the pull request changes UI. ## Closing issues Fixes # ## After Merge * [ ] Does this change invalidate any docs or tutorials? _If so ensure the changes needed are either made or recorded_ * [ ] Does this change require a release to be made? Is so please create and deploy the release ================================================ FILE: .github/workflows/ci.yaml ================================================ on: push: { "branches": [ "main" ] } pull_request: { "branches": [ "main" ] } jobs: test: runs-on: ubuntu-latest name: OTP ${{matrix.otp}} / Elixir ${{matrix.elixir}} strategy: matrix: otp: ['23.0'] elixir: ['1.11.3'] steps: - uses: actions/checkout@v2 - uses: erlef/setup-elixir@v1 with: otp-version: ${{matrix.otp}} elixir-version: ${{matrix.elixir}} - run: MIX_ENV=test mix deps.get - run: MIX_ENV=test mix test - run: MIX_ENV=test mix credo --strict ================================================ FILE: .github/workflows/greetings.yml ================================================ name: Greetings on: [pull_request, issues] jobs: greeting: runs-on: ubuntu-latest steps: - uses: actions/first-interaction@v1 with: repo-token: ${{ secrets.GITHUB_TOKEN }} issue-message: 'Thank you for submitting an issue! It means a lot that you took the time -- it helps us be better 🙏' pr-message: "Thank you for submitting a PR 🎉 It's very appreciated!" ================================================ FILE: .gitignore ================================================ /_build /cover /deps /doc erl_crash.dump *.ez *.beam .DS_Store .mix ================================================ FILE: .tool-versions ================================================ erlang 24.2 elixir 1.13.2 ================================================ FILE: LICENSE ================================================ The MIT License (MIT) Copyright (c) 2017 Brooklyn Zelenka Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ================================================ FILE: README.md ================================================ ![](https://github.com/robot-overlord/algae/blob/main/brand/logo.png?raw=true) [![Build Status](https://travis-ci.org/expede/algae.svg?branch=master)](https://travis-ci.org/expede/algae) [![Inline docs](http://inch-ci.org/github/expede/algae.svg?branch=master)](http://inch-ci.org/github/expede/algae) [![Deps Status](https://beta.hexfaktor.org/badge/all/github/expede/algae.svg)](https://beta.hexfaktor.org/github/expede/algae) [![hex.pm version](https://img.shields.io/hexpm/v/algae.svg?style=flat)](https://hex.pm/packages/algae) [![API Docs](https://img.shields.io/badge/api-docs-yellow.svg?style=flat)](http://hexdocs.pm/algae/) [![license](https://img.shields.io/github/license/mashape/apistatus.svg?maxAge=2592000)](https://github.com/expede/algae/blob/master/LICENSE) Algae provides a boilerplate-avoiding DSL for defining algebraic data types (ADTs), plus several common structures # Quickstart Add Algae to your list of dependencies in `mix.exs`: ```elixir def deps do [{:algae, "~> 1.2"}] end ``` # Table of Contents - [Product Builder](#product-builder) - [Definition DSL](#definition-dsl) - [Constructor](#constructor) - [Empty Tag](#empty-tag) - [Sum Builder](#sum-builder) - [Default Constructor](#default-constructor) - [Tagged Unions](#tagged-unions) - [A Sampling of ADTs](#a-sampling-of-adts) - [`Id`](#algaeid) - [`Maybe`](#algaemaybe) - [`Tree.BinarySearch`](#algaetreebinarysearch) --- > **NOTE** > Please `import Algae` before trying out the examples below. > The samples assume that is has already been done to remove > the unnecessary clutter. --- # Product Builder Build a product type Includes: * Struct * Type definition * Constructor function (for piping and defaults) * Implicit defaults for simple values ## Definition DSL For convenience, several variants of the DSL are available. ### Standard ```elixir defmodule Player do # =============== # # Data Definition # # =============== # defdata do name :: String.t() hit_points :: non_neg_integer() experience :: non_neg_integer() end # =================== # # Rest of Module # # (business as usual) # # =================== # @spec attack(t(), t()) :: {t(), t()} def attack(%{experience: xp} = player, %{hit_points: hp} = target) do { %{player | experience: xp + 50}, %{target | hit_points: hp - 10} } end end #=> %Player{name: "Sir Bob", hit_points: 10, experience: 500} ``` ### Single Field Shorthand Without any fields specified, Algae will default to a single field with the same name as the module (essentially a "wrapper type"). You must still provide the type for this field, however. Embedded in another module: ```elixir defmodule Id do defdata any() end %Id{} #=> %Id{id: nil} ``` Standalone: ```elixir defdata Wrapper :: any() %Wrapper{} #=> %Wrapper{wrapper: nil} ``` ## Constructor A helper function, especially useful for piping. The order of arguments is the same as the order that they are defined in. ```elixir defmodule Person do defdata do name :: String.t() age :: non_neg_integer() end end Person.new("Rachel Weintraub") #=> %Person{ # name: "Rachel Weintraub", # age: 0 # } ``` ### Constructor Defaults Fields will automatically default to a sensible value (a typical "zero" for that datatype). For example, `non_neg_integer()` will default to `0`, and `String.t()` will default to `""`. You may also overwrite these defaults with the `\\` syntax. ```elixir defmodule Pet do defdata do name :: String.t() leg_count :: non_neg_integer() \\ 4 end end Pet.new("Crookshanks") #=> %Pet{ # name: "Crookshanks", # leg_count: 4 # } Pet.new("Paul the Psychic Octopus", 8) #=> %Pet{ # name: "Paul the Psychic Octopus", # leg_count: 8 # } ``` This overwriting syntax is _required_ for complex types: ```elixir defdata Grocery do item :: {String.t(), integer(), boolean()} \\ {"Orange", 4, false} end Grocery.new() #=> %Grocery{ # item: {"Orange", 4, false} # } ``` ### Overwrite Constructor The `new` constructor function may be overwritten. ```elixir defmodule Constant do defdata :: fun() def new(value), do: %Constant{constant: fn _ -> value end} end fourty_two = Constant.new(42) fourty_two.constant.(33) #=> 42 ``` ## Empty Tag An empty type (with no fields) is definable using the `none`() type ```elixir defmodule Nothing do defdata none() end Nothing.new() #=> %Nothing{} ``` # Sum Builder Build a sum (coproduct) type from product types ```elixir defmodule Light do # ============== # # Sum Definition # # ============== # defsum do defdata Red :: none() defdata Yellow :: none() defdata Green :: none() end # =================== # # Rest of Module # # (business as usual) # # =================== # def from_number(1), do: %Light.Red{} def from_number(2), do: %Light.Yellow{} def from_number(3), do: %Light.Green{} end Light.new() #=> %Light.Red{} ``` ## Embedded Products Data with multiple fields can be defined directly as part of a sum ```elixir defmodule Pet do defsum do defdata Cat do name :: String.t() claw_sharpness :: String.t() end defdata Dog do name :: String.t() bark_loudness :: non_neg_integer() end end end ``` ## Default Constructor The first `defdata`'s constructor will be the default constructor for the sum ```elixir defmodule Maybe do defsum do defdata Nothing :: none() defdata Just :: any() end end Maybe.new() #=> %Maybe.Nothing{} ``` ## Tagged Unions Sums join existing types with tags: new types to help distinguish the context that they are in (the sum type) ```elixir defdata Book :: String.t() \\ "War and Peace" defdata Video :: String.t() \\ "2001: A Space Odyssey" defmodule Media do defsum do defdata Paper :: Book.t() defdata Film :: Video.t() \\ Video.new("A Clockwork Orange") end end media = Media.new() #=> %Paper{ # paper: %Book{ # book: "War and Peace" # } # } ``` # A Sampling of ADTs See [complete docs](https://hexdocs.pm/algae) for more ## `Algae.Id` The simplest ADT: a simple wrapper for some data ```elixir %Algae.Id{id: "hi!"} ``` ## `Algae.Maybe` Maybe represents the presence or absence of something. Please note that `nil` is actually a value, as it can be passed to functions! `nil` is not bottom! ```elixir Algae.Maybe.new() #=> %Algae.Maybe.Nothing{} Algae.Maybe.new(42) #=> %Algae.Maybe.Just{just: 42} ``` ## `Tree.BinarySearch` ```elixir alias Algae.Tree.BinarySearch, as: BTree # 42 # / \ # 77 1234 # / \ # 98 32 BTree.Branch.new( 42, BTree.Branch.new(77), BTree.Branch.new( 1234, BTree.Branch.new(98), BTree.Branch.new(32) ) ) #=> %Algae.Tree.BinarySearch.Branch{ # value: 42, # left: %Algae.Tree.BinarySearch.Branch{ # value: 77, # left: %Algae.Tree.BinarySearch.Empty{}, # right: %Algae.Tree.BinarySearch.Empty{} # }, # right: %Algae.Tree.BinarySearch.Branch{ # value: 1234, # left: %Algae.Tree.BinarySearch.Branch{ # value: 98, # left: %Algae.Tree.BinarySearch.Empty{}, # right: %Algae.Tree.BinarySearch.Empty{} # }, # right: %Algae.Tree.BinarySearch.Branch{ # value: 32, # left: %Algae.Tree.BinarySearch.Empty{}, # right: %Algae.Tree.BinarySearch.Empty{} # } # } # } ``` ================================================ FILE: brand/LOGO_LICENSE ================================================ ORIGINAL AUTHOR ATTRIBUTION: Gabriele Kothe-Heinrich DESCRIPTION: Halidrys siliquosa (L.) 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If the standard suite of rights granted under applicable copyright law includes additional rights not granted under this License, such additional rights are deemed to be included in the License; this License is not intended to restrict the license of any rights under applicable law. ================================================ FILE: lib/algae/either.ex ================================================ defmodule Algae.Either do @moduledoc ~S""" Represent branching conditions. These could be different return types, error vs nominal value, and so on. ## Examples iex> require Integer ...> ...> even_odd = fn(value) -> ...> if Integer.is_even(value) do ...> Algae.Either.Right.new(value) ...> else ...> Algae.Either.Left.new(value) ...> end ...> end ...> ...> even_odd.(10) %Algae.Either.Right{right: 10} ...> even_odd.(11) %Algae.Either.Left{left: 11} """ import Algae defsum do defdata Left :: any() defdata Right :: any() end end alias Algae.Either.{Left, Right} import TypeClass use Witchcraft ############# # Generator # ############# defimpl TypeClass.Property.Generator, for: Algae.Either.Left do def generate(_) do [1, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() |> Algae.Either.Left.new() end end defimpl TypeClass.Property.Generator, for: Algae.Either.Right do def generate(_) do [1, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() |> Algae.Either.Right.new() end end ########## # Setoid # ########## definst Witchcraft.Setoid, for: Algae.Either.Left do def equivalent?(_, %Right{}), do: false def equivalent?(%Left{left: a}, %Left{left: b}), do: Witchcraft.Setoid.equivalent?(a, b) end definst Witchcraft.Setoid, for: Algae.Either.Right do def equivalent?(_, %Left{}), do: false def equivalent?(%Right{right: a}, %Right{right: b}), do: Witchcraft.Setoid.equivalent?(a, b) end ####### # Ord # ####### definst Witchcraft.Ord, for: Algae.Either.Left do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Left.new() end def compare(_, %Algae.Either.Right{}), do: :lesser def compare(%Left{left: a}, %Left{left: b}), do: Witchcraft.Ord.compare(a, b) end definst Witchcraft.Ord, for: Algae.Either.Right do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Right.new() end def compare(_, %Left{}), do: :greater def compare(%Right{right: a}, %Right{right: b}), do: Witchcraft.Ord.compare(a, b) end ############# # Semigroup # ############# definst Witchcraft.Semigroup, for: Algae.Either.Left do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Left.new() end def append(left, %Right{}), do: left def append(%Left{left: a}, %Left{left: b}), do: %Left{left: a <> b} end definst Witchcraft.Semigroup, for: Algae.Either.Right do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Algae.Either.Right.new() end def append(_, left = %Left{}), do: left def append(%Right{right: a}, %Right{right: b}), do: %Right{right: a <> b} end ########## # Monoid # ########## definst Witchcraft.Monoid, for: Algae.Either.Left do def empty(%Left{left: a}), do: %Right{right: Witchcraft.Monoid.empty(a)} end definst Witchcraft.Monoid, for: Algae.Either.Right do def empty(%Right{right: a}), do: %Right{right: Witchcraft.Monoid.empty(a)} end # ########### # # Functor # # ########### definst Witchcraft.Functor, for: Algae.Either.Left do def map(left, _), do: left end definst Witchcraft.Functor, for: Algae.Either.Right do def map(%Right{right: data}, fun), do: data |> fun.() |> Right.new() end # ############ # # Foldable # # ############ definst Witchcraft.Foldable, for: Algae.Either.Left do def right_fold(_, seed, _), do: seed end definst Witchcraft.Foldable, for: Algae.Either.Right do def right_fold(%Right{right: inner}, seed, fun), do: fun.(inner, seed) end # ############### # # Traversable # # ############### definst Witchcraft.Traversable, for: Algae.Either.Left do @force_type_instance true def traverse(left = %Left{left: value}, link) do value |> link.() |> of(left) end end definst Witchcraft.Traversable, for: Algae.Either.Right do def traverse(%Right{right: value}, link), do: map(link.(value), &Right.new/1) end # ######### # # Apply # # ######### definst Witchcraft.Apply, for: Algae.Either.Left do def convey(left, _), do: left end definst Witchcraft.Apply, for: Algae.Either.Right do def convey(_, left = %Left{}), do: left def convey(data, %Right{right: fun}), do: map(data, fun) end ############### # Applicative # ############### definst Witchcraft.Applicative, for: Algae.Either.Left do @force_type_instance true def of(_, data), do: Right.new(data) end definst Witchcraft.Applicative, for: Algae.Either.Right do def of(_, data), do: Right.new(data) end # ######### # # Chain # # ######### definst Witchcraft.Chain, for: Algae.Either.Left do def chain(left, _), do: left end definst Witchcraft.Chain, for: Algae.Either.Right do def chain(%Right{right: data}, link), do: link.(data) end # ######### # # Monad # # ######### definst Witchcraft.Monad, for: Algae.Either.Left definst Witchcraft.Monad, for: Algae.Either.Right # ########## # # Extend # # ########## definst Witchcraft.Extend, for: Algae.Either.Left do def nest(_), do: Left.new() end definst Witchcraft.Extend, for: Algae.Either.Right do def nest(inner), do: Right.new(inner) end ================================================ FILE: lib/algae/free.ex ================================================ defmodule Algae.Free do @moduledoc """ A "free" structure that converts functors into monads by embedding them in a special structure with all of the monadic heavy lifting done for you. Similar to trees and lists, but with the ability to add a struct "tag", at each level. Often used for DSLs, interpreters, or building structured data. For a simple introduction to the "free monad + interpreter" pattern, we recommend [Why free monads matter](http://www.haskellforall.com/2012/06/you-could-have-invented-free-monads.html). ## Anatomy ### Pure `Pure` simply holds a plain value. %Free.Pure{pure: 42} ### Roll `Roll` resursively containment of more `Free` structures embedded in a another ADT. For example, with `Id`: %Free.Roll{ roll: %Id{ id: %Pure{ pure: 42 } } } """ alias __MODULE__ alias Algae.Free.{Pure, Roll} import Algae use Witchcraft defsum do defdata(Roll :: any()) defdata(Pure :: any() \\ %Witchcraft.Unit{}) end @doc """ Create an `Algae.Free.Pure` wrapping a single, simple value ## Examples iex> new(42) %Algae.Free.Pure{pure: 42} """ @spec new(any()) :: t() def new(value), do: %Pure{pure: value} @doc """ Add another layer to a free structure ## Examples iex> 13 ...> |> new() ...> |> layer(%Algae.Id{}) %Algae.Free.Roll{ roll: %Algae.Id{ id: %Algae.Free.Pure{ pure: 13 } } } """ @spec layer(t(), any()) :: t() def layer(free, mutual), do: %Roll{roll: of(mutual, free)} @doc """ Wrap a functor in a free structure. ## Examples iex> wrap(%Algae.Id{id: 42}) %Algae.Free.Roll{ roll: %Algae.Id{ id: 42 } } """ @spec wrap(Witchcraft.Functor.t()) :: Roll.t() def wrap(functor), do: %Roll{roll: functor} @doc """ Lift a plain functor up into a free monad. ## Examples iex> free(%Algae.Id{id: 42}) %Algae.Free.Roll{ roll: %Algae.Id{ id: %Algae.Free.Pure{ pure: 42 } } } """ @spec free(Witchcraft.Functor.t()) :: t() def free(functor) do functor |> map(&of(%Roll{}, &1)) |> wrap() end end alias Algae.Free alias Algae.Free.{Pure, Roll} alias TypeClass.Property.Generator alias Witchcraft.{Apply, Chain, Functor, Ord, Setoid} import TypeClass use Witchcraft ############# # Generator # ############# defimpl TypeClass.Property.Generator, for: Algae.Free.Pure do def generate(_) do [1, 1.1, "", []] |> Enum.random() |> Generator.generate() |> Pure.new() end end defimpl TypeClass.Property.Generator, for: Algae.Free.Roll do def generate(_) do inner = Algae.Id.new() seed = [1, 1.1, "", []] |> Enum.random() |> Generator.generate() seed |> Free.new() |> Free.layer(inner) |> Free.layer(inner) end end ########## # Setoid # ########## definst Witchcraft.Setoid, for: Algae.Free.Pure do custom_generator(_) do 1 |> Generator.generate() |> Pure.new() end def equivalent?(_, %Roll{}), do: false def equivalent?(%Pure{pure: a}, %Pure{pure: b}), do: Setoid.equivalent?(a, b) end definst Witchcraft.Setoid, for: Algae.Free.Roll do custom_generator(_) do inner = Algae.Id.new() seed = Generator.generate(1) seed |> Free.new() |> Free.layer(inner) |> Free.layer(inner) end def equivalent?(_, %Pure{}), do: false def equivalent?(%Roll{roll: a}, %Roll{roll: b}), do: Setoid.equivalent?(a, b) end ####### # Ord # ####### definst Witchcraft.Ord, for: Algae.Free.Pure do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Free.new() end def compare(_, %Roll{}), do: :lesser def compare(%Pure{pure: a}, %Pure{pure: b}), do: Ord.compare(a, b) end definst Witchcraft.Ord, for: Algae.Free.Roll do custom_generator(_) do inner = Algae.Id.new() seed = Generator.generate(1) seed |> Free.new() |> Free.layer(inner) |> Free.layer(inner) end def compare(%Roll{}, %Pure{}), do: :greater def compare(%Roll{roll: a}, %Roll{roll: b}), do: Ord.compare(a, b) end ########### # Functor # ########### definst Witchcraft.Functor, for: Algae.Free.Pure do def map(%Pure{pure: data}, fun), do: %Pure{pure: fun.(data)} end definst Witchcraft.Functor, for: Algae.Free.Roll do def map(%Roll{roll: data}, fun) do data |> Functor.map(&Functor.map(&1, fun)) |> Roll.new() end end ######### # Apply # ######### definst Witchcraft.Apply, for: Algae.Free.Pure do def convey(%Pure{pure: data}, %Pure{pure: fun}), do: %Pure{pure: fun.(data)} def convey(pure, %Roll{roll: rolled}) do rolled |> Functor.map(&Apply.convey(pure, &1)) |> Roll.new() end end definst Witchcraft.Apply, for: Algae.Free.Roll do def convey(%Roll{roll: rolled}, %Pure{pure: fun}) do rolled |> Functor.map(&Functor.map(&1, fun)) |> Roll.new() end def convey(roll, %Roll{roll: rolled}) do rolled |> Functor.map(&Apply.convey(roll, &1)) |> Roll.new() end end ############### # Applicative # ############### definst Witchcraft.Applicative, for: Algae.Free.Pure do def of(_, value), do: %Pure{pure: value} end definst Witchcraft.Applicative, for: Algae.Free.Roll do def of(_, value), do: %Pure{pure: value} end ######### # Chain # ######### definst Witchcraft.Chain, for: Algae.Free.Pure do def chain(%Pure{pure: pure}, link), do: link.(pure) end definst Witchcraft.Chain, for: Algae.Free.Roll do def chain(%Roll{roll: rolled}, link) do rolled |> Functor.map(&Chain.chain(&1, link)) |> Roll.new() end end ######### # Monad # ######### definst(Witchcraft.Monad, for: Algae.Free.Pure) definst(Witchcraft.Monad, for: Algae.Free.Roll) ================================================ FILE: lib/algae/id/applicative.ex ================================================ import TypeClass definst Witchcraft.Applicative, for: Algae.Id do def of(_, data), do: Algae.Id.new(data) end ================================================ FILE: lib/algae/id/apply.ex ================================================ import TypeClass use Witchcraft definst Witchcraft.Apply, for: Algae.Id do def convey(data, %{id: fun}), do: map(data, fun) end ================================================ FILE: lib/algae/id/chain.ex ================================================ import TypeClass definst Witchcraft.Chain, for: Algae.Id do def chain(%{id: data}, link), do: link.(data) end ================================================ FILE: lib/algae/id/comonad.ex ================================================ import TypeClass definst Witchcraft.Comonad, for: Algae.Id do def extract(%{id: inner}), do: inner end ================================================ FILE: lib/algae/id/extend.ex ================================================ import TypeClass definst Witchcraft.Extend, for: Algae.Id do def nest(inner), do: Algae.Id.new(inner) end ================================================ FILE: lib/algae/id/foldable.ex ================================================ import TypeClass definst Witchcraft.Foldable, for: Algae.Id do def right_fold(%{id: data}, seed, fun), do: fun.(data, seed) end ================================================ FILE: lib/algae/id/functor.ex ================================================ import TypeClass definst Witchcraft.Functor, for: Algae.Id do def map(%{id: data}, fun), do: data |> fun.() |> Algae.Id.new() end ================================================ FILE: lib/algae/id/generator.ex ================================================ defimpl TypeClass.Property.Generator, for: Algae.Id do def generate(_) do [1, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() |> Algae.Id.new() end end ================================================ FILE: lib/algae/id/monad.ex ================================================ import TypeClass definst Witchcraft.Monad, for: Algae.Id ================================================ FILE: lib/algae/id/monoid.ex ================================================ import TypeClass definst Witchcraft.Monoid, for: Algae.Id do def empty(%{id: sample}), do: sample |> Witchcraft.Monoid.empty() |> Algae.Id.new() end ================================================ FILE: lib/algae/id/ord.ex ================================================ import TypeClass use Witchcraft definst Witchcraft.Ord, for: Algae.Id do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Algae.Id.new() end def compare(%{id: a}, %{id: b}), do: Witchcraft.Ord.compare(a, b) end ================================================ FILE: lib/algae/id/semigroup.ex ================================================ import TypeClass use Witchcraft definst Witchcraft.Semigroup, for: Algae.Id do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Algae.Id.new() end def append(%{id: a}, %{id: b}), do: %Algae.Id{id: a <> b} end ================================================ FILE: lib/algae/id/setoid.ex ================================================ import TypeClass use Witchcraft definst Witchcraft.Setoid, for: Algae.Id do def equivalent?(%{id: a}, %{id: b}), do: a == b end ================================================ FILE: lib/algae/id/traversable.ex ================================================ import TypeClass use Witchcraft definst Witchcraft.Traversable, for: Algae.Id do def traverse(%{id: data}, link) do data |> link.() |> map(&Algae.Id.new/1) end end ================================================ FILE: lib/algae/id.ex ================================================ defmodule Algae.Id do @moduledoc ~S""" The simplest ADT: a simple wrapper for some data ## Examples iex> %Algae.Id{id: "hi!"} %Algae.Id{id: "hi!"} """ import Algae defdata any() @doc """ Wrap some data in an `Algae.Id` wrapper ## Examples iex> new(42) %Algae.Id{id: 42} """ @spec new(any()) :: t() def new(inner), do: %Algae.Id{id: inner} end ================================================ FILE: lib/algae/internal/needs_explicit_default_error.ex ================================================ defmodule Algae.Internal.NeedsExplicitDefaultError do defexception message: "Needs explicit default value" end ================================================ FILE: lib/algae/internal.ex ================================================ defmodule Algae.Internal do @moduledoc false @type ast() :: {atom(), any(), any()} @doc """ Construct a data type AST """ @spec data_ast(module(), Macro.Env.t() | [module()], ast()) :: ast() def data_ast(lines, %{aliases: _} = caller) when is_list(lines) do {field_values, field_types, specs, args, defaults} = module_elements(lines, caller) arg_count = Enum.count(args) overridables = Enum.map(0..arg_count, &({:new_partial, &1})) ++ [new: arg_count] # More verbose, but clearer. # for arity <- 0..Enum.count(args) do # {:new, arity} # end args_without_defaults = Enum.map(args, fn({:\\, [], [stripped, _]}) -> stripped end) quote do use Quark @type t :: %__MODULE__{unquote_splicing(field_types)} defstruct unquote(field_values) defpartial new_partial(unquote_splicing(args_without_defaults)) do struct(__MODULE__, unquote(defaults)) end @doc "Positional constructor, with args in the same order as they were defined in" @spec new(unquote_splicing(specs)) :: t() def new(unquote_splicing(args)) do struct(__MODULE__, unquote(defaults)) end defoverridable unquote(overridables) end end def data_ast(modules, {:none, _, _}) do full_module = modules |> List.wrap() |> Module.concat() quote do defmodule unquote(full_module) do @type t :: %__MODULE__{} defstruct [] @doc "Default #{__MODULE__} struct" @spec new() :: t() def new, do: struct(__MODULE__) defoverridable [new: 0] end end end def data_ast(caller_module, type) do default = default_value(type) field = module_to_field(caller_module) quote do @type t :: %unquote(caller_module){ unquote(field) => unquote(type) } defstruct [{unquote(field), unquote(default)}] @doc "Default #{__MODULE__} struct" @spec new() :: t() def new, do: struct(__MODULE__) @doc "Constructor helper for piping" @spec new(unquote(type)) :: t() def new(field), do: struct(__MODULE__, [unquote(field), field]) defoverridable [new: 0, new: 1] end end @spec data_ast([module()], any(), ast()) :: ast() def data_ast(name, default, type_ctx) do full_module = Module.concat(name) field = module_to_field(name) quote do defmodule unquote(full_module) do @type t :: %unquote(full_module){ unquote(field) => unquote(type_ctx) } defstruct [{unquote(field), unquote(default)}] @doc "Default #{__MODULE__} struct. Value defaults to #{inspect unquote(default)}." @spec new() :: t() def new, do: struct(__MODULE__) @doc "Helper for initializing struct with a specific value" @spec new(unquote(type_ctx)) :: t() def new(value), do: struct(__MODULE__, [{unquote(field), value}]) end end end @spec embedded_data_ast() :: ast() def embedded_data_ast do quote do @type t :: %__MODULE__{} defstruct [] @doc "Default #{__MODULE__} struct" @spec new() :: t() def new, do: struct(__MODULE__) end end def embedded_data_ast(module_ctx, default, type_ctx) do field = module_to_field(module_ctx) quote do @type t :: %__MODULE__{ unquote(field) => unquote(type_ctx) } defstruct [{unquote(field), unquote(default)}] @doc "Default #{__MODULE__} struct" @spec new(unquote(type_ctx)) :: t() def new(field \\ unquote(default)), do: struct(__MODULE__, [field]) defoverridable [new: 1] end end @type field :: {atom(), [any()], [any()]} @type type :: {atom(), [any()], [any()]} @spec module_elements([ast()], Macro.Env.t()) :: { [{field(), any()}], [{field(), type()}], [type], [{:\\, [], any()}], [{field(), any()}] } def module_elements(lines, caller) do List.foldr(lines, {[], [], [], [], []}, fn(line, {value_acc, type_acc, typespec_acc, acc_arg, acc_mapping}) -> {field, type, default_value} = normalize_elements(line, caller) arg = {field, [], Elixir} { [{field, default_value} | value_acc], [{field, type} | type_acc], [type | typespec_acc], [{:\\, [], [arg, default_value]} | acc_arg], [{field, arg} | acc_mapping] } end) end @spec normalize_elements(ast(), Macro.Env.t()) :: {atom(), type(), any()} def normalize_elements({:::, _, [{field, _, _}, type]}, caller) do expanded_type = resolve_alias(type, caller) {field, expanded_type, default_value(expanded_type)} end def normalize_elements({:\\, _, [{:::, _, [{field, _, _}, type]}, default]}, _) do {field, type, default} end @spec resolve_alias(ast(), Macro.Env.t()) :: ast() def resolve_alias({{_, _, _} = a, b, c}, caller) do {resolve_alias(a, caller), b, c} end def resolve_alias({:. = a, b, [{:__aliases__, _, _} = the_alias | rest]}, caller) do resolved_alias = Macro.expand(the_alias, caller) {a, b, [resolved_alias | rest]} end def resolve_alias(a, _), do: a @spec or_types([ast()], module()) :: [ast()] def or_types({:\\, _, [{:::, _, [_, types]}, _]}, module_ctx) do or_types(types, module_ctx) end def or_types([head | tail], module_ctx) do Enum.reduce(tail, call_type(head, module_ctx), fn(module, acc) -> {:|, [], [call_type(module, module_ctx), acc]} end) end @spec modules(module(), [module()]) :: [module()] def modules(top, module_ctx), do: [top | extract_name(module_ctx)] @spec call_type(module(), [module()]) :: ast() def call_type(new_module, module_ctx) do full_module = List.wrap(module_ctx) ++ submodule_name(new_module) {{:., [], [{:__aliases__, [alias: false], full_module}, :t]}, [], []} end @spec submodule_name({:defdata, any(), [{:::, any(), [any()]}]}) :: [module()] def submodule_name({:defdata, _, [{:::, _, [body, _]}]}) do body |> case do {:\\, _, [inner_module_ctx, _]} -> inner_module_ctx {:__aliases__, _, module} -> module outer_module_ctx -> outer_module_ctx end |> List.wrap() end def submodule_name({:defdata, _, [{:\\, _, [{:::, _, [{:__aliases__, _, module}, _]}, _]}]}) do List.wrap(module) end def submodule_name({:defdata, _, [{:__aliases__, _, module}, _]}) do List.wrap(module) end @spec extract_name({any(), any(), atom()} | [module()]) :: [module()] def extract_name({_, _, inner_name}), do: List.wrap(inner_name) def extract_name(module_chain) when is_list(module_chain), do: module_chain def module_to_field(modules) when is_list(modules) do modules |> List.last() |> module_to_field() end def module_to_field(module) do module |> Atom.to_string() |> String.split(".") |> List.last() |> String.downcase() |> String.trim_leading("elixir.") |> String.to_atom() end # credo:disable-for-lines:21 Credo.Check.Refactor.CyclomaticComplexity def default_value({{:., _, [{_, _, [:String]}, :t]}, _, _}), do: "" def default_value({{:., _, [String, :t]}, _, _}), do: "" def default_value({{:., _, [{_, _, adt}, :t]}, _, []}) do quote do: unquote(Module.concat(adt)).new() end def default_value({{:., _, [module, :t]}, _, []}) do quote do: unquote(module).new() end def default_value([_]), do: [] def default_value({type, _, _}) do type |> case do :boolean -> false :number -> 0 :integer -> 0 :float -> 0.0 :pos_integer -> 1 :non_neg_integer -> 0 :bitstring -> "" :charlist -> [] [] -> [] :list -> [] :map -> %{} :fun -> &Quark.id/1 :-> -> &Quark.id/1 :any -> nil :t -> raise %Algae.Internal.NeedsExplicitDefaultError{message: "Type is lone `t`"} atom -> atom end |> Macro.escape() end end ================================================ FILE: lib/algae/maybe.ex ================================================ defmodule Algae.Maybe do @moduledoc ~S""" The sum of `Algae.Maybe.Just` and `Algae.Maybe.Nothing`. Maybe represents the presence or absence of something. Please note that `nil` is actually a value, as it can be passed to functions! `nil` is not bottom! ## Examples iex> [1,2,3] ...> |> List.first() ...> |> case do ...> nil -> new() ...> head -> new(head) ...> end %Algae.Maybe.Just{just: 1} iex> [] ...> |> List.first() ...> |> case do ...> nil -> new() ...> head -> new(head) ...> end %Algae.Maybe.Nothing{} """ import Algae alias Algae.Maybe.{Just, Nothing} defsum do defdata Nothing :: none() defdata Just :: any() end @doc ~S""" Put no value into the `Maybe` context (ie: make it a `Nothing`) ## Examples iex> new() %Algae.Maybe.Nothing{} """ @spec new() :: Nothing.t() defdelegate new, to: Nothing, as: :new @doc ~S""" Put a value into the `Maybe` context (ie: make it a `Just`) ## Examples iex> new(9) %Algae.Maybe.Just{just: 9} iex> new(nil) %Algae.Maybe.Just{just: nil} iex> new(nil, nothing: nil) %Algae.Maybe.Nothing{} iex> new(9, nothing: 9) %Algae.Maybe.Nothing{} iex> new(9, nothing: 1) %Algae.Maybe.Just{just: 9} """ @spec new(any(), [nothing: any()]) :: Just.t() | Nothing.t() def new(nothing_value, [nothing: nothing_value]), do: Nothing.new() def new(value, _), do: Just.new(value) @spec new(any()) :: Just.t() def new(value), do: Just.new(value) @doc """ Alias for `new(value, nothing: nil)`. ## Examples iex> from_nillable(9) %Algae.Maybe.Just{just: 9} iex> from_nillable(nil) %Algae.Maybe.Nothing{} """ @spec from_nillable(any()) :: Just.t() def from_nillable(value), do: new(value, nothing: nil) @doc """ Extract a value from a `Maybe`, falling back to a set value in the `Nothing` case. ## Examples iex> from_maybe(%Algae.Maybe.Nothing{}, else: 42) 42 iex> %Algae.Maybe.Just{just: 1955} |> from_maybe(else: 42) 1955 """ @spec from_maybe(t(), any()) :: any() def from_maybe(%Nothing{}, [else: fallback]), do: fallback def from_maybe(%Just{just: inner}, _), do: inner end alias Algae.Maybe.{Just, Nothing} import TypeClass use Witchcraft ############# # Generator # ############# defimpl TypeClass.Property.Generator, for: Algae.Maybe.Nothing do def generate(_), do: Nothing.new() end defimpl TypeClass.Property.Generator, for: Algae.Maybe.Just do def generate(_) do [1, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() |> Just.new() end end ########## # Setoid # ########## definst Witchcraft.Setoid, for: Algae.Maybe.Nothing do def equivalent?(_, %Nothing{}), do: true def equivalent?(_, %Just{}), do: false end definst Witchcraft.Setoid, for: Algae.Maybe.Just do def equivalent?(%Just{just: a}, %Just{just: b}), do: Witchcraft.Setoid.equivalent?(a, b) def equivalent?(%Just{}, %Nothing{}), do: false end ####### # Ord # ####### definst Witchcraft.Ord, for: Algae.Maybe.Nothing do def compare(_, %Nothing{}), do: :equal def compare(_, %Just{}), do: :lesser end definst Witchcraft.Ord, for: Algae.Maybe.Just do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Just.new() end def compare(%Just{just: a}, %Just{just: b}), do: Witchcraft.Ord.compare(a, b) def compare(%Just{}, %Nothing{}), do: :greater end ############# # Semigroup # ############# definst Witchcraft.Semigroup, for: Algae.Maybe.Nothing do def append(_, right), do: right end definst Witchcraft.Semigroup, for: Algae.Maybe.Just do custom_generator(_) do 1 |> TypeClass.Property.Generator.generate() |> Just.new() end def append(%Just{just: a}, %Just{just: b}), do: %Just{just: a <> b} def append(just, %Nothing{}), do: just end ########## # Monoid # ########## definst Witchcraft.Monoid, for: Algae.Maybe.Nothing do def empty(nothing), do: nothing end definst Witchcraft.Monoid, for: Algae.Maybe.Just do def empty(_), do: %Algae.Maybe.Nothing{} end ########### # Functor # ########### definst Witchcraft.Functor, for: Algae.Maybe.Nothing do def map(_, _), do: %Algae.Maybe.Nothing{} end definst Witchcraft.Functor, for: Algae.Maybe.Just do def map(%{just: data}, fun), do: data |> fun.() |> Algae.Maybe.Just.new() end ############ # Foldable # ############ definst Witchcraft.Foldable, for: Algae.Maybe.Nothing do def right_fold(_, seed, _), do: seed end definst Witchcraft.Foldable, for: Algae.Maybe.Just do def right_fold(%Just{just: inner}, seed, fun), do: fun.(inner, seed) end ############### # Traversable # ############### # Not traversable because we don't have enough type information for Nothing ######### # Apply # ######### definst Witchcraft.Apply, for: Algae.Maybe.Nothing do def convey(_, _), do: %Algae.Maybe.Nothing{} end definst Witchcraft.Apply, for: Algae.Maybe.Just do alias Algae.Maybe.{Just, Nothing} def convey(data, %Nothing{}), do: %Nothing{} def convey(data, %Just{just: fun}), do: map(data, fun) end ############### # Applicative # ############### definst Witchcraft.Applicative, for: Algae.Maybe.Nothing do def of(_, data), do: Just.new(data) end definst Witchcraft.Applicative, for: Algae.Maybe.Just do def of(_, data), do: Just.new(data) end ######### # Chain # ######### definst Witchcraft.Chain, for: Algae.Maybe.Nothing do def chain(_, _), do: %Nothing{} end definst Witchcraft.Chain, for: Algae.Maybe.Just do def chain(%{just: data}, link), do: link.(data) end ######### # Monad # ######### definst Witchcraft.Monad, for: Algae.Maybe.Nothing definst Witchcraft.Monad, for: Algae.Maybe.Just ########## # Extend # ########## definst Witchcraft.Extend, for: Algae.Maybe.Nothing do def nest(_), do: %Nothing{} end definst Witchcraft.Extend, for: Algae.Maybe.Just do def nest(inner), do: Just.new(inner) end ================================================ FILE: lib/algae/reader/applicative.ex ================================================ alias Algae.Reader import TypeClass use Witchcraft definst Witchcraft.Applicative, for: Algae.Reader do @force_type_instance true def of(_, value), do: Reader.new(fn _ -> value end) end ================================================ FILE: lib/algae/reader/apply.ex ================================================ alias Algae.Reader import TypeClass use Quark use Witchcraft definst Witchcraft.Apply, for: Algae.Reader do @force_type_instance true def convey(%Reader{reader: fun_a}, %Reader{reader: fun_b}) do Reader.new(fn e -> curry(fun_a).(e).(fun_b.(e)) end) end end ================================================ FILE: lib/algae/reader/chain.ex ================================================ import TypeClass definst Witchcraft.Chain, for: Algae.Reader do @force_type_instance true alias Algae.Reader def chain(reader, link) do Reader.new(fn e -> reader |> Reader.run(e) |> link.() |> Reader.run(e) end) end end ================================================ FILE: lib/algae/reader/functor.ex ================================================ alias Algae.Reader import TypeClass use Witchcraft definst Witchcraft.Functor, for: Algae.Reader do @force_type_instance true def map(%Reader{reader: inner}, fun), do: Reader.new(fn e -> e |> inner.() |> fun.() end) end ================================================ FILE: lib/algae/reader/generator.ex ================================================ defimpl TypeClass.Property.Generator, for: Algae.Reader do def generate(_) do fn -> nil end |> TypeClass.Property.Generator.generate() |> Algae.Reader.new() end end ================================================ FILE: lib/algae/reader/monad.ex ================================================ import TypeClass definst Witchcraft.Monad, for: Algae.Reader do @force_type_instance true end ================================================ FILE: lib/algae/reader.ex ================================================ defmodule Algae.Reader do @moduledoc ~S""" `Algae.Reader` allows you to pass some readable context around through actions. This is useful in a number of situations, but the most common case is to weave access to environment variables monadically. For an illustrated guide to `Reader`s, see [Thee Useful Monads](http://adit.io/posts/2013-06-10-three-useful-monads.html#the-state-monad). ## Examples iex> use Witchcraft ...> iex> correct = ...> monad %Algae.Reader{} do ...> count <- ask &Map.get(&1, :count) ...> bindings <- ask() ...> return (count == map_size(bindings)) ...> end ...> iex> sample_bindings = %{count: 3, a: 1, b: 2} iex> correct_count = run(correct, sample_bindings) iex> "Correct count for #{inspect sample_bindings}? #{correct_count}" "Correct count for %{a: 1, b: 2, count: 3}? true" ...> iex> bad_bindings = %{count: 100, a: 1, b: 2} iex> bad_count = run(correct, bad_bindings) iex> "Correct count for #{inspect bad_bindings}? #{bad_count}" "Correct count for %{a: 1, b: 2, count: 100}? false" Example adapted from [source](https://hackage.haskell.org/package/mtl-2.2.1/docs/Control-Monad-Reader.html) """ alias __MODULE__ import Algae use Witchcraft defdata fun() @doc """ `Reader` constructor. ## Examples iex> newbie = new(fn x -> x * 10 end) ...> newbie.reader.(10) 100 """ @spec new(fun()) :: t() def new(fun), do: %Reader{reader: fun} @doc """ Run the reader function with some argument. iex> reader = new(fn x -> x + 5 end) ...> run(reader, 42) 47 This is the opposite of `new/1`. iex> fun = fn x -> x + 5 end ...> fun.(42) == fun |> new() |> run(42) true """ @spec run(t(), any()) :: any() def run(%Reader{reader: fun}, arg), do: fun.(arg) @doc """ Get the wrapped environment. Especially useful in monadic do-notation. ## Examples iex> run(ask(), 42) 42 iex> use Witchcraft ...> ...> example_fun = ...> fn x -> ...> monad %Algae.Reader{} do ...> e <- ask() ...> return {x, e} ...> end ...> end ...> ...> 42 ...> |> example_fun.() ...> |> run(7) {42, 7} """ @spec ask() :: t() def ask, do: Reader.new(fn x -> x end) @doc ~S""" Similar to `new/1` and `ask/0`. Construct an `Algae.Reader`, but apply a function to the constructed envoronment. The pun here is that you're "asking" a function for something. ## Examples iex> fn x -> x * 10 end ...> |> ask() ...> |> run(5) 50 iex> use Witchcraft ...> ...> foo = ...> fn words -> ...> monad %Algae.Reader{} do ...> loud <- ask &(&1 == String.upcase(&1)) ...> return(words <> (if loud, do: "!", else: ".")) ...> end ...> end ...> ...> "Hello" |> foo.() |> run("WORLD") # "WORLD" is the context being asked for "Hello!" """ @spec ask((any() -> any())) :: t() def ask(fun) do monad %Reader{} do e <- ask return fun.(e) end end @doc """ Locally composes a function into a `Reader`. Often the idea is to temporarily adapt the `Reader` without continuing this change in later `run`s. ## Examples iex> ask() ...> |> local(fn word -> word <> "!" end) ...> |> local(&String.upcase/1) ...> |> run("o hai thar") "O HAI THAR!" """ @spec local(t(), (any() -> any())) :: any() def local(reader, fun) do monad %Reader{} do e <- ask return run(reader, fun.(e)) end end end ================================================ FILE: lib/algae/state/applicative.ex ================================================ import TypeClass definst Witchcraft.Applicative, for: Algae.State do @force_type_instance true def of(_, value), do: %Algae.State{runner: fn x -> {value, x} end} end ================================================ FILE: lib/algae/state/apply.ex ================================================ alias Algae.State import TypeClass definst Witchcraft.Apply, for: Algae.State do @force_type_instance true def convey(%State{runner: state_g}, %State{runner: state_f}) do fg = fn(s) -> {x, t} = state_f.(s) {y, u} = state_g.(t) {x.(y), u} end State.new(fn x -> fg.(x) end) end end ================================================ FILE: lib/algae/state/chain.ex ================================================ alias Algae.State import TypeClass definst Witchcraft.Chain, for: Algae.State do @force_type_instance true def chain(state, link) do State.state(fn s -> {x, z} = State.run(state, s) State.run(link.(x), z) end) end end ================================================ FILE: lib/algae/state/functor.ex ================================================ alias Algae.State import TypeClass definst Witchcraft.Functor, for: Algae.State do @force_type_instance true def map(%State{runner: inner}, fun) do run_map = fn({a, b}, f) -> {f.(a), b} end st_tuple = fn(g, s) -> g |> State.new() |> State.run(s) end State.new(fn x -> inner |> st_tuple.(x) |> run_map.(fun) end) end end ================================================ FILE: lib/algae/state/generator.ex ================================================ defimpl TypeClass.Property.Generator, for: Algae.State do def generate(_) do inner = [0, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() Algae.State.new(fn x -> {inner, x} end) end end ================================================ FILE: lib/algae/state/monad.ex ================================================ import TypeClass definst Witchcraft.Monad, for: Algae.State do @force_type_instance true end ================================================ FILE: lib/algae/state.ex ================================================ defmodule Algae.State do @moduledoc ~S""" `Algae.State` describes a wrapped function that can be used to pass around some "hidden" pure state. This has numerous applications, but the primary advantage is purity. The state gets passed around with the value, and the monadic DSL helps it feel more natural than passing everything around by hand. In many ways, `Algae.State` is a generalization of `Algae.Reader` and `Algae.Writer`. See [Thee Useful Monads](http://adit.io/posts/2013-06-10-three-useful-monads.html#the-state-monad) a nice, illustrated guide to how these work and relate. ## Anatomy # To pass in concrete values ↓ %Algae.State{runner: fn access -> {value, state} end} ↑ ↑ # "explicit" value position "hidden" state position ## Examples iex> use Witchcraft ...> ...> %Algae.State{} ...> |> monad do ...> name <- get() ...> let result = "Hello, #{name}!" ...> ...> put result ...> modify &String.upcase/1 ...> ...> return result ...> end ...> |> run("world") { "Hello, world!", "HELLO, WORLD!" } iex> use Witchcraft ...> ...> pop = fn -> state(fn([x | xs]) -> {x, xs} end) end ...> pull = fn -> state(fn(list = [x | _]) -> {x, list} end) end ...> push = &state(fn(xs) -> {%Witchcraft.Unit{}, [&1 | xs]} end) ...> ...> %Algae.State{} ...> |> monad do ...> push.(["a"]) ...> push.(["b"]) ...> push.(["c"]) ...> push.(["d"]) ...> push.(["e"]) ...> ...> z <- pop.() ...> y <- pop.() ...> x <- pop.() ...> ...> push.(x <> y <> z) ...> pull.() ...> end ...> |> evaluate([]) ["c", "d", "e"] """ alias __MODULE__ alias Witchcraft.Unit use Witchcraft @type runner :: (any() -> {any(), any()}) @type t :: %State{runner: runner()} defstruct [runner: &State.default/1] @spec default(any()) :: {integer(), any()} def default(s), do: {s, s} @doc """ Construct a new `Algae.State` struct from a state runner in the form `fn x -> {y, z} end` ## Examples iex> new(fn x -> {x + 1, x} end).runner.(42) {43, 42} """ @spec new(State.runner()) :: State.t() def new(runner), do: %State{runner: runner} @doc """ Alias for `new/1` that reads better when importing the module. ## Examples iex> state(fn x -> {x + 1, x} end).runner.(42) {43, 42} """ @spec state(State.runner()) :: State.t() def state(runner), do: new(runner) @doc """ Extract the runner from an `Algae.State`. Can be used as a curried version of `run/2`. ## Examples iex> inner = fn x -> {0, x} end ...> ...> run(%Algae.State{runner: inner}).(42) == inner.(42) true """ @spec run(State.t()) :: State.runner() def run(%State{runner: fun}), do: fun @doc """ Run an `Algae.State` by passing in some initial state to actualy run the enclosed state runner. ## Examples iex> use Witchcraft ...> ...> %Algae.State{} ...> |> of(2) ...> |> run(0) {2, 0} """ @spec run(State.t(), any()) :: any() def run(%State{runner: fun}, arg), do: fun.(arg) @doc """ Set the stateful position of an `Algae.Struct`. Not unlike `Algae.Writer.tell/1`. ## Examples iex> 1 ...> |> put() ...> |> run(0) {%Witchcraft.Unit{}, 1} """ @spec put(any()) :: State.t() def put(s), do: State.new(fn _ -> {%Unit{}, s} end) @doc ~S""" Run a function over the "state" portion of the runner. ## Examples iex> fn x -> x + 1 end ...> |> modify() ...> |> run(42) {%Witchcraft.Unit{}, 43} iex> use Witchcraft ...> ...> %Algae.State{} ...> |> monad do ...> name <- get() ...> ...> put "State" ...> modify &String.upcase/1 ...> ...> return "Hello, #{name}!" ...> end ...> |> run("world") {"Hello, world!", "STATE"} """ @spec modify((any() -> any())) :: State.t() def modify(fun), do: State.new(fn s -> {%Unit{}, fun.(s)} end) @doc """ Set both sides of an `Algae.State` struct. ## Examples iex> run(get(), 1) {1, 1} """ @spec get() :: State.t() def get, do: State.new(fn a -> {a, a} end) @doc """ Set both sides of an `Algae.State` struct, plus running a function over the value portion of the inner state. ## Examples iex> fn x -> x * 10 end ...> |> get() ...> |> run(4) {40, 4} """ @spec get((any() -> any())) :: State.t() def get(fun) do monad %Algae.State{} do s <- get() return fun.(s) end end @doc ~S""" Run the enclosed `Algae.State` runner, and return the value (no state). ## Examples iex> use Witchcraft ...> ...> %Algae.State{} ...> |> monad do ...> name <- get() ...> put "Ignored" ...> return "Hello, #{name}!" ...> end ...> |> evaluate("world") "Hello, world!" """ @spec evaluate(State.t(), any()) :: any() def evaluate(state, value) do state |> run(value) |> elem(0) end @doc ~S""" Run the enclosed `Algae.State` runner, and return the state (no value). ## Examples iex> fn x -> x + 1 end ...> |> get() ...> |> execute(1) 1 iex> use Witchcraft ...> ...> %Algae.State{} ...> |> monad do ...> whatevs <- get() ...> put "State" ...> return "Hello, #{whatevs}!" ...> end ...> |> execute("world") "State" """ @spec execute(State.t(), any()) :: any() def execute(state, value) do state |> run(value) |> elem(1) end end ================================================ FILE: lib/algae/tree/binary_search/applicative.ex ================================================ alias Algae.Tree.BinarySearch.Node import TypeClass use Witchcraft definst Witchcraft.Applicative, for: Algae.Tree.BinarySearch.Empty do def of(_, data), do: %Node{node: data} end definst Witchcraft.Applicative, for: Algae.Tree.BinarySearch.Node do @force_type_instance true def of(_, data), do: %Node{node: data} end ================================================ FILE: lib/algae/tree/binary_search/apply.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Apply, for: Algae.Tree.BinarySearch.Empty do def convey(_, _), do: %Empty{} end definst Witchcraft.Apply, for: Algae.Tree.BinarySearch.Node do def convey(_, %Empty{}), do: %Empty{} def convey(%{node: node, left: left, right: right}, tree_funs = %Node{node: fun}) do %Node{ node: fun.(node), left: Witchcraft.Apply.convey(left, tree_funs), right: Witchcraft.Apply.convey(right, tree_funs) } end end ================================================ FILE: lib/algae/tree/binary_search/chain.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Chain, for: Algae.Tree.BinarySearch.Empty do def chain(_, _), do: %Empty{} end definst Witchcraft.Chain, for: Algae.Tree.BinarySearch.Node do def chain(%Node{node: node}, link), do: link.(node) end ================================================ FILE: lib/algae/tree/binary_search/extend.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Extend, for: Algae.Tree.BinarySearch.Empty do def nest(_), do: %Empty{} end definst Witchcraft.Extend, for: Algae.Tree.BinarySearch.Node do def nest(tree = %Node{left: left, right: right}) do %Node{ node: tree, left: Witchcraft.Extend.nest(left), right: Witchcraft.Extend.nest(right) } end end ================================================ FILE: lib/algae/tree/binary_search/foldable.ex ================================================ alias Algae.Tree.BinarySearch.Node import TypeClass use Witchcraft definst Witchcraft.Foldable, for: Algae.Tree.BinarySearch.Empty do def right_fold(_, seed, _), do: seed end definst Witchcraft.Foldable, for: Algae.Tree.BinarySearch.Node do def right_fold(%Node{node: node, left: left, right: right}, seed, fun) do folded_right = Witchcraft.Foldable.right_fold(right, seed, fun) folded_left = Witchcraft.Foldable.right_fold(left, folded_right, fun) fun.(node, folded_left) end end ================================================ FILE: lib/algae/tree/binary_search/functor.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} alias Witchcraft.Functor import TypeClass definst Witchcraft.Functor, for: Algae.Tree.BinarySearch.Empty do def map(_, _), do: %Empty{} end definst Witchcraft.Functor, for: Algae.Tree.BinarySearch.Node do def map(%Node{node: node, left: left, right: right}, fun) do %Node{ node: fun.(node), left: Functor.map(left, fun), right: Functor.map(right, fun) } end end ================================================ FILE: lib/algae/tree/binary_search/generator.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} use Witchcraft defimpl TypeClass.Property.Generator, for: Algae.Tree.BinarySearch.Empty do def generate(_), do: Empty.new() end defimpl TypeClass.Property.Generator, for: Algae.Tree.BinarySearch.Node do def generate(_) do random_node() end def random_node do case Enum.random(Enum.to_list(0..5)) do 0 -> %Node{node: random_value()} 1 -> %Node{node: random_value()} 2 -> %Node{ node: random_value(), left: random_node(), right: random_node() } _ -> %Empty{} end end def random_value do [1, 1.1, "", []] |> Enum.random() |> TypeClass.Property.Generator.generate() end end ================================================ FILE: lib/algae/tree/binary_search/monad.ex ================================================ import TypeClass use Witchcraft definst(Witchcraft.Monad, for: Algae.Tree.BinarySearch.Empty) definst Witchcraft.Monad, for: Algae.Tree.BinarySearch.Node do @force_type_instance true end ================================================ FILE: lib/algae/tree/binary_search/monoid.ex ================================================ alias Algae.Tree.BinarySearch, as: BST alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Monoid, for: Algae.Tree.BinarySearch.Empty do def empty(empty), do: empty end definst Witchcraft.Monoid, for: Algae.Tree.BinarySearch.Node do def empty(_), do: %Empty{} end ================================================ FILE: lib/algae/tree/binary_search/ord.ex ================================================ alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Ord, for: Algae.Tree.BinarySearch.Empty do def compare(_, %Empty{}), do: :equal def compare(_, %Node{}), do: :lesser end definst Witchcraft.Ord, for: Algae.Tree.BinarySearch.Node do custom_generator(_) do random_node() end def random_node do Enum.random([ %Empty{}, %Empty{}, %Empty{}, %Node{ node: random_value() }, %Node{ node: random_value(), left: random_value(), right: random_value() } ]) end def random_value, do: TypeClass.Property.Generator.generate(1) def compare(%Node{}, %Empty{}), do: :greater def compare(%Node{node: a}, %Node{node: b}), do: Witchcraft.Ord.compare(a, b) end ================================================ FILE: lib/algae/tree/binary_search/semigroup.ex ================================================ alias Algae.Tree.BinarySearch, as: BST alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Semigroup, for: Algae.Tree.BinarySearch.Empty do def append(_, %Empty{}), do: %Empty{} def append(_, node = %Node{}), do: node end definst Witchcraft.Semigroup, for: Algae.Tree.BinarySearch.Node do def append(node, %Empty{}), do: node def append(node_a, node_b) do node_a |> BST.to_list() |> Enum.concat(BST.to_list(node_b)) |> BST.from_list() end end ================================================ FILE: lib/algae/tree/binary_search/setoid.ex ================================================ alias Algae.Tree.BinarySearch, as: BST alias Algae.Tree.BinarySearch.{Empty, Node} import TypeClass use Witchcraft definst Witchcraft.Setoid, for: Algae.Tree.BinarySearch.Empty do def equivalent?(_, %Empty{}), do: true def equivalent?(_, %Node{}), do: false end definst Witchcraft.Setoid, for: Algae.Tree.BinarySearch.Node do def equivalent?(%Node{}, %Empty{}), do: false def equivalent?(%Node{node: a}, %Node{node: b}) do Witchcraft.Setoid.equivalent?(a, b) end end ================================================ FILE: lib/algae/tree/binary_search.ex ================================================ defmodule Algae.Tree.BinarySearch do @moduledoc """ Represent a `BinarySearch` tree. ## Examples iex> alias Algae.Tree.BinarySearch, as: BSTree ...> ...> BSTree.Node.new( ...> 42, ...> BSTree.Node.new(77), ...> BSTree.Node.new( ...> 1234, ...> BSTree.Node.new(98), ...> BSTree.Node.new(32) ...> ) ...> ) %Algae.Tree.BinarySearch.Node{ node: 42, left: %Algae.Tree.BinarySearch.Node{ node: 77, left: %Algae.Tree.BinarySearch.Empty{}, right: %Algae.Tree.BinarySearch.Empty{} }, right: %Algae.Tree.BinarySearch.Node{ node: 1234, left: %Algae.Tree.BinarySearch.Node{ node: 98, left: %Algae.Tree.BinarySearch.Empty{}, right: %Algae.Tree.BinarySearch.Empty{} }, right: %Algae.Tree.BinarySearch.Node{ node: 32, left: %Algae.Tree.BinarySearch.Empty{}, right: %Algae.Tree.BinarySearch.Empty{} } } } """ alias __MODULE__ alias BinarySearch.{Empty, Node} import Algae use Witchcraft, except: [to_list: 1] defsum do defdata(Empty :: none()) defdata Node do node :: any() left :: BinarySearch.t() \\ BinarySearch.Empty.new() right :: BinarySearch.t() \\ BinarySearch.Empty.new() end end @doc """ Create an empty tree. ## Examples iex> new() %Algae.Tree.BinarySearch.Empty{} """ @spec new() :: Empty.t() def new, do: %Empty{} @doc """ Bring a value into an otherwise empty tree. ## Examples iex> new(42) %Algae.Tree.BinarySearch.Node{ node: 42, left: %Algae.Tree.BinarySearch.Empty{}, right: %Algae.Tree.BinarySearch.Empty{} } """ @spec new(any()) :: Node.t() def new(value), do: %Node{node: value} @doc """ Insert a new element into a tree. ## Examples iex> insert(new(42), 43) %Algae.Tree.BinarySearch.Node{ node: 42, right: %Algae.Tree.BinarySearch.Node{ node: 43 } } """ @spec insert(t(), any()) :: t() def insert(%Empty{}, value), do: new(value) def insert(tree = %Node{node: node, left: left, right: right}, orderable) do case compare(orderable, node) do :equal -> tree :greater -> %{tree | right: insert(right, orderable)} :lesser -> %{tree | left: insert(left, orderable)} end end def insert(%Empty{}, value), do: new(value) def insert(tree = %Node{node: node, left: left, right: right}, orderable) do case compare(orderable, node) do :equal -> tree :greater -> %{tree | right: insert(right, orderable)} :lesser -> %{tree | left: insert(left, orderable)} end end @doc """ Remove an element from a tree by value. ## Examples iex> alias Algae.Tree.BinarySearch, as: BSTree ...> ...> BSTree.Node.new( ...> 42, ...> BSTree.Node.new(77), ...> BSTree.Node.new( ...> 1234, ...> BSTree.Node.new(98), ...> BSTree.Node.new(32) ...> ) ...> ) |> delete(98) %Algae.Tree.BinarySearch.Node{ node: 42, left: %Algae.Tree.BinarySearch.Node{ node: 77 }, right: %Algae.Tree.BinarySearch.Node{ node: 1234, right: %Algae.Tree.BinarySearch.Node{ node: 32 } } } """ @spec delete(t(), any()) :: t() def delete(%Empty{}, _), do: %Empty{} def delete(tree = %Node{node: node, left: left, right: right}, orderable) do case compare(orderable, node) do :greater -> %{tree | right: delete(right, orderable)} :lesser -> %{tree | left: delete(left, orderable)} :equal -> case tree do %{left: %Empty{}} -> right %{right: %Empty{}} -> left %{right: %{node: shift}} -> %{tree | node: shift, right: delete(right, shift)} end end end @doc """ Flatten a tree into a list. ## Examples iex> alias Algae.Tree.BinarySearch, as: BSTree ...> ...> BSTree.Node.new( ...> 42, ...> BSTree.Node.new(77), ...> BSTree.Node.new( ...> 1234, ...> BSTree.Node.new(98), ...> BSTree.Node.new(32) ...> ) ...> ) ...> |> BSTree.to_list() [42, 77, 1234, 98, 32] """ @spec to_list(t()) :: list() def to_list(tree), do: Witchcraft.Foldable.to_list(tree) @doc """ Flatten a tree into a list with elements sorted. ## Examples iex> alias Algae.Tree.BinarySearch, as: BSTree ...> ...> BSTree.Node.new( ...> 42, ...> BSTree.Node.new(77), ...> BSTree.Node.new( ...> 1234, ...> BSTree.Node.new(98), ...> BSTree.Node.new(32) ...> ) ...> ) ...> |> BSTree.to_ordered_list() [32, 42, 77, 98, 1234] """ @spec to_ordered_list(t()) :: list() def to_ordered_list(tree), do: tree |> to_list() |> Enum.sort() @doc """ Build a `BinarySearch` tree from a list. ## Examples iex> Algae.Tree.BinarySearch.from_list([42, 77, 1234, 98, 32]) %Algae.Tree.BinarySearch.Node{ node: 42, left: %Algae.Tree.BinarySearch.Node{ node: 32 }, right: %Algae.Tree.BinarySearch.Node{ node: 77, right: %Algae.Tree.BinarySearch.Node{ node: 1234, left: %Algae.Tree.BinarySearch.Node{ node: 98 } } } } """ @spec from_list(list()) :: t() def from_list([]), do: %Empty{} def from_list([head | tail]), do: from_list(tail, new(head)) @doc """ Build a `BinarySearch` tree from a list and attach to an existing tree. ## Examples iex> Algae.Tree.BinarySearch.from_list([42, 77, 1234, 98, 32], new(-9)) %Algae.Tree.BinarySearch.Node{ node: -9, right: %Algae.Tree.BinarySearch.Node{ left: %Algae.Tree.BinarySearch.Node{ node: 32 }, node: 42, right: %Algae.Tree.BinarySearch.Node{ node: 77, right: %Algae.Tree.BinarySearch.Node{ node: 1234, left: %Algae.Tree.BinarySearch.Node{ node: 98 }, right: %Algae.Tree.BinarySearch.Empty{} } } } } """ @spec from_list(list(), t()) :: t() def from_list([], seed), do: seed def from_list([head | tail], seed), do: from_list(tail, insert(seed, head)) end ================================================ FILE: lib/algae/tree/rose/applicative.ex ================================================ import TypeClass definst Witchcraft.Applicative, for: Algae.Tree.Rose do def of(_, value), do: Algae.Tree.Rose.new(value) end ================================================ FILE: lib/algae/tree/rose/apply.ex ================================================ alias Algae.Tree.Rose alias Witchcraft.{Apply, Functor} import TypeClass definst Witchcraft.Apply, for: Algae.Tree.Rose do def convey(tree = %Rose{rose: rose, forest: forest}, %Rose{rose: fun, forest: funs}) do new_forest = Functor.map(forest, &Functor.map(&1, fun)) ++ Functor.map(funs, &Apply.convey(tree, &1)) %Rose{ rose: fun.(rose), forest: new_forest } end end ================================================ FILE: lib/algae/tree/rose/chain.ex ================================================ alias Algae.Tree.Rose alias Witchcraft.{Chain, Functor} import TypeClass definst Witchcraft.Chain, for: Algae.Tree.Rose do def chain(%Rose{rose: rose, forest: forest}, link) do %Rose{rose: new_rose, forest: mid_forest} = link.(rose) new_forest = mid_forest ++ Functor.map(forest, &Chain.chain(&1, link)) Rose.new(new_rose, new_forest) end end ================================================ FILE: lib/algae/tree/rose/foldable.ex ================================================ alias Algae.Tree.Rose alias Witchcraft.Foldable import TypeClass definst Witchcraft.Foldable, for: Algae.Tree.Rose do def right_fold(%Rose{rose: rose, forest: forest}, acc, fun) do fun.(rose, Foldable.right_fold(forest, acc, fun)) end end ================================================ FILE: lib/algae/tree/rose/functor.ex ================================================ alias Algae.Tree.Rose alias Witchcraft.Functor import TypeClass definst Witchcraft.Functor, for: Algae.Tree.Rose do def map(%Rose{rose: rose, forest: forest}, fun) do %Rose{ rose: fun.(rose), forest: Functor.map(forest, &Functor.map(&1, fun)) } end end ================================================ FILE: lib/algae/tree/rose/generator.ex ================================================ alias Algae.Tree.Rose alias TypeClass.Property.Generator defimpl TypeClass.Property.Generator, for: Algae.Tree.Rose do def generate(_) do case Enum.random(0..2) do 0 -> Rose.new(rose(), forest()) _ -> Rose.new(rose()) end end def forest do fn -> case Enum.random(0..10) do 0 -> Rose.new(rose(), forest()) _ -> Rose.new(rose()) end end |> Stream.repeatedly() |> Enum.take(Enum.random(0..5)) end def rose do [1, 1.1, "", []] |> Enum.random() |> Generator.generate() end end ================================================ FILE: lib/algae/tree/rose/monad.ex ================================================ import TypeClass definst Witchcraft.Monad, for: Algae.Tree.Rose ================================================ FILE: lib/algae/tree/rose.ex ================================================ defmodule Algae.Tree.Rose do @moduledoc """ A tree with any number of nodes at each level ## Examples %Algae.Tree.Rose{ rose: 42, forest: [ %Algae.Tree.Rose{ rose: "hi" }, %Algae.Tree.Rose{ forest: [ %Algae.Tree.Rose{ rose: 0.4 } ] }, %Algae.Tree.Rose{ rose: "there" } ] } """ alias __MODULE__ import Algae @type rose :: any() @type forest :: [t()] defdata do rose :: any() forest :: [t()] end @doc """ Create a simple `Algae.Rose` tree, with an empty forest and one rose. ## Examples iex> new(42) %Algae.Tree.Rose{ rose: 42, forest: [] } """ @spec new(rose()) :: t() def new(rose), do: %Rose{rose: rose, forest: []} @doc """ Create an `Algae.Rose` tree, passing a forest and a rose. ## Examples iex> new(42, [new(55), new(14)]) %Algae.Tree.Rose{ rose: 42, forest: [ %Algae.Tree.Rose{rose: 55}, %Algae.Tree.Rose{rose: 14} ] } """ @spec new(rose(), forest()) :: t() def new(rose, forest), do: %Rose{rose: rose, forest: forest} @doc """ Wrap another tree around an existing one, relegating it to the forest. ## Examples iex> 55 ...> |> new() ...> |> layer(42) ...> |> layer(99) ...> |> layer(6) %Algae.Tree.Rose{ rose: 6, forest: [ %Algae.Tree.Rose{ rose: 99, forest: [ %Algae.Tree.Rose{ rose: 42, forest: [ %Algae.Tree.Rose{ rose: 55 } ] } ] } ] } """ @spec layer(t(), rose()) :: t() def layer(tree, rose), do: %Rose{rose: rose, forest: [tree]} end ================================================ FILE: lib/algae/writer/applicative.ex ================================================ alias Algae.Writer import TypeClass use Witchcraft definst Witchcraft.Applicative, for: Algae.Writer do def of(%Writer{writer: {_, log}}, value), do: Writer.new(value, empty(log)) end ================================================ FILE: lib/algae/writer/apply.ex ================================================ alias Algae.Writer import TypeClass use Quark use Witchcraft definst Witchcraft.Apply, for: Algae.Writer do def convey(%Writer{writer: {value, log_a}}, %Writer{writer: {fun, log_b}}) do Writer.new(fun.(value), log_b <> log_a) end end ================================================ FILE: lib/algae/writer/chain.ex ================================================ alias Algae.Writer import TypeClass use Witchcraft definst Witchcraft.Chain, for: Algae.Writer do def chain(%Writer{writer: {old_value, old_log}}, link) do %Writer{writer: {new_value, new_log}} = link.(old_value) Writer.new(new_value, old_log <> new_log) end end ================================================ FILE: lib/algae/writer/functor.ex ================================================ alias Algae.Writer import TypeClass use Witchcraft definst Witchcraft.Functor, for: Algae.Writer do def map(%Writer{writer: {value, log}}, fun), do: Writer.new(fun.(value), log) end ================================================ FILE: lib/algae/writer/generator.ex ================================================ alias TypeClass.Property.Generator defimpl TypeClass.Property.Generator, for: Algae.Writer do def generate(_), do: Algae.Writer.new({Generator.generate(0), Generator.generate("")}) end ================================================ FILE: lib/algae/writer/monad.ex ================================================ import TypeClass definst Witchcraft.Monad, for: Algae.Writer ================================================ FILE: lib/algae/writer.ex ================================================ defmodule Algae.Writer do @moduledoc ~S""" `Algae.Writer` helps capture the pattern of writing to a pure log or accumulated value, handling the bookkeeping for you. If `Algae.Reader` is quasi-read-only, `Algae.Writer` is quasi-write-only. This is often used for loggers, but could be anything as long as the hidden value is a `Witchcraft.Monoid`. There are many applications of `Writer`s, but as an illustrative point, one could use it for logging across processes and time, since the log is carried around with the result in a pure fashion. The monadic DSL helps make using these feel more natural. For an illustrated guide to `Writer`s, see [Thee Useful Monads](http://adit.io/posts/2013-06-10-three-useful-monads.html#the-state-monad). ## Anatomy %Algae.Writer{writer: {value, log}} ↑ ↑ # "explicit" value position "hidden" position, # commonly used as a log ## Examples iex> use Witchcraft ...> ...> excite = ...> fn string -> ...> monad writer({0.0, "log"}) do ...> tell string ...> ...> excited <- return "#{string}!" ...> tell " => #{excited} ... " ...> ...> return excited ...> end ...> end ...> ...> {_, logs} = ...> "Hi" ...> |> excite.() ...> >>> excite ...> >>> excite ...> |> censor(&String.trim_trailing(&1, " ... ")) ...> |> run() ...> ...> logs "Hi => Hi! ... Hi! => Hi!! ... Hi!! => Hi!!!" iex> use Witchcraft ...> ...> exponent = ...> fn num -> ...> monad writer({0, 0}) do ...> tell 1 ...> return num * num ...> end ...> end ...> ...> initial = 42 ...> {result, times} = run(exponent.(initial) >>> exponent >>> exponent) ...> ...> "#{initial}^#{round(:math.pow(2, times))} = #{result}" "42^8 = 9682651996416" """ alias __MODULE__ alias Witchcraft.{Monoid, Unit} use Witchcraft @type log :: Monoid.t() @type value :: any() @type writer :: {Writer.value(), Writer.log()} @type t :: %Writer{writer: writer()} defstruct writer: {0, []} @doc """ Construct a `Algae.Writer` struct from a starting value and log. ## Examples iex> new() %Algae.Writer{writer: {0, []}} iex> new("hi") %Algae.Writer{writer: {"hi", []}} iex> new("ohai", 42) %Algae.Writer{writer: {"ohai", 42}} """ @spec new(any(), Monoid.t()) :: Writer.t() def new(value \\ 0, log \\ []), do: %Writer{writer: {value, log}} @doc """ Similar to `new/2`, but taking a tuple rather than separate fields. ## Examples iex> writer({"ohai", 42}) %Algae.Writer{writer: {"ohai", 42}} """ @spec writer(Writer.writer()) :: Writer.t() def writer({value, log}), do: new(value, log) @doc ~S""" Extract the enclosed value and log from an `Algae.Writer`. ## Examples iex> run(%Algae.Writer{writer: {"hi", "there"}}) {"hi", "there"} iex> use Witchcraft ...> ...> half = ...> fn num -> ...> monad writer({0.0, ["log"]}) do ...> let half = num / 2 ...> tell ["#{num} / 2 = #{half}"] ...> return half ...> end ...> end ...> ...> run(half.(42) >>> half >>> half) { 5.25, [ "42 / 2 = 21.0", "21.0 / 2 = 10.5", "10.5 / 2 = 5.25" ] } """ @spec run(Writer.t()) :: Writer.value() def run(%Writer{writer: writer}), do: writer @doc ~S""" Set the "log" portion of an `Algae.Writer` step ## Examples iex> tell("secrets") %Algae.Writer{writer: {%Witchcraft.Unit{}, "secrets"}} iex> use Witchcraft ...> ...> monad %Algae.Writer{writer: {"string", 1}} do ...> tell 42 ...> tell 43 ...> return "hey" ...> end %Algae.Writer{writer: {"hey", 85}} iex> use Witchcraft ...> ...> half = ...> fn num -> ...> monad writer({0.0, ["log"]}) do ...> let half = num / 2 ...> tell ["#{num} / 2 = #{half}"] ...> return half ...> end ...> end ...> ...> run(half.(42.0) >>> half >>> half) { 5.25, [ "42.0 / 2 = 21.0", "21.0 / 2 = 10.5", "10.5 / 2 = 5.25" ] } """ @spec tell(Writer.log()) :: Writer.t() def tell(log), do: new(%Unit{}, log) @doc """ Copy the log into the value position. This makes it accessible in do-notation. ## Examples iex> listen(%Algae.Writer{writer: {42, "hi"}}) %Algae.Writer{writer: {{42, "hi"}, "hi"}} iex> use Witchcraft ...> ...> monad new(1, 1) do ...> wr <- listen tell(42) ...> tell 43 ...> return wr ...> end %Algae.Writer{ writer: {{%Witchcraft.Unit{}, 42}, 85} } """ @spec listen(Writer.t()) :: Writer.t() def listen(%Writer{writer: {value, log}}), do: %Writer{writer: {{value, log}, log}} @doc """ Similar to `listen/1`, but with the ability to adjust the copied log. ## Examples iex> listen(%Algae.Writer{writer: {1, "hi"}}, &String.upcase/1) %Algae.Writer{ writer: {{1, "HI"}, "hi"} } """ @spec listen(Writer.t(), (log() -> log())) :: Writer.t() def listen(writer, fun) do monad writer do {value, log} <- listen writer return {value, fun.(log)} end end @doc ~S""" Run a function in the value portion of an `Algae.Writer` on the log. Notice that the structure is similar to what somes out of `listen/{1,2}` Algae.Writer{writer: {{_, function}, log}} ## Examples iex> pass(%Algae.Writer{writer: {{1, fn x -> x * 10 end}, 42}}) %Algae.Writer{writer: {1, 420}} iex> use Witchcraft ...> ...> monad new("string", ["logs"]) do ...> a <- ["start"] |> tell() |> listen() ...> tell ["middle"] ...> ...> {value, logs} <- return a ...> pass writer({{value, fn [log | _] -> [log | [log | logs]] end}, logs}) ...> ...> tell ["next is 42"] ...> return 42 ...> end %Algae.Writer{ writer: {42, ["start", "middle", "start", "start", "start", "next is 42"]} } """ @spec pass(Writer.t()) :: Writer.t() def pass(%Writer{writer: {{value, fun}, log}}), do: %Writer{writer: {value, fun.(log)}} @doc ~S""" Run a writer, and run a function over the resulting log. ## Examples iex> 42 ...> |> new(["hi", "THERE", "friend"]) ...> |> censor(&Enum.reject(&1, fn log -> String.upcase(log) == log end)) ...> |> run() {42, ["hi", "friend"]} iex> use Witchcraft ...> ...> 0 ...> |> new(["logs"]) ...> |> monad do ...> tell ["Start"] ...> tell ["BANG!"] ...> tell ["shhhhhhh..."] ...> tell ["LOUD NOISES!!!"] ...> tell ["End"] ...> ...> return 42 ...> end ...> |> censor(&Enum.reject(&1, fn log -> String.upcase(log) == log end)) ...> |> run() {42, ["Start", "shhhhhhh...", "End"]} """ @spec censor(Writer.t(), (any() -> any())) :: Writer.t() def censor(writer, fun) do pass(monad writer do value <- writer return {value, fun} end) end end ================================================ FILE: lib/algae.ex ================================================ defmodule Algae do @moduledoc """ Builder DSL to handle common ADT definition use cases """ import Algae.Internal @type ast() :: {atom(), any(), any()} @doc ~S""" Build a product type Includes: * Struct * Type definition * Constructor function (for piping and defaults) * Implicit defaults for simple values ## Definition For convenveniece, several variants of the DSL are available. ### Standard defmodule Player do # =============== # # Data Definition # # =============== # defdata do name :: String.t() hit_points :: non_neg_integer() experience :: non_neg_integer() end # =================== # # Rest of Module # # (business as usual) # # =================== # @spec attack(t(), t()) :: {t(), t()} def attack(%{experience: xp} = player, %{hit_points: hp} = target) do { %{player | experience: xp + 50}, %{target | hit_points: hp - 10} } end end #=> %Player{name: "Sir Bob", hit_points: 10, experience: 500} ### Single Field Shorthand Without any fields specified, Algae will default to a single field with the same name as the module (essentially a "wrapper type"). You must still provide the type for this field, however. Embedded in another module: defmodule Id do defdata any() end %Id{} #=> %Id{id: nil} Standalone: defdata Wrapper :: any() %Wrapper{} #=> %Wrapper{wrapper: nil} ## Constructor A helper function, especially useful for piping. The order of arguments is the same as the order that they are defined in. defmodule Person do defdata do name :: String.t() age :: non_neg_integer() end end Person.new("Rachel Weintraub") #=> %Person{ # name: "Rachel Weintraub", # age: 0 # } ### Constructor Defaults Fields will automatically default to a sensible value (a typical "zero" for that datatype). For example, `non_neg_integer()` will default to `0`, and `String.t()` will default to `""`. You may also overwrite these defaults with the `\\\\` syntax. defmodule Pet do defdata do name :: String.t() leg_count :: non_neg_integer() \\\\ 4 end end Pet.new("Crookshanks") #=> %Pet{ # name: "Crookshanks", # leg_count: 4 # } Pet.new("Paul the Psychic Octopus", 8) #=> %Pet{ # name: "Paul the Psychic Octopus", # leg_count: 8 # } This overwriting syntax is _required_ for complex types: defdata Grocery do item :: {String.t(), integer(), boolean()} \\\\ {"Apple", 4, false} end Grocery.new() #=> %Grocery{ # item: {"Apple", 4, false} # } ### Overwrite Constructor The `new` constructor function may be overwritten. iex> defmodule Constant do ...> defdata fun() ...> ...> def new(value), do: %Constant{constant: fn _ -> value end} ...> end ...> ...> fourty_two = Constant.new(42) ...> fourty_two.constant.(33) 42 ## Empty Tag An empty type (with no fields) is definable using the `none`() type defmodule Nothing do defdata none() end Nothing.new() #=> %Nothing{} """ defmacro defdata(ast) do caller_module = __CALLER__.module case ast do {:none, _, _} = type -> embedded_data_ast() {:\\, _, [{:::, _, [module_ctx, type]}, default]} -> caller_module |> modules(module_ctx) |> data_ast(default, type) {:\\, _, [type, default]} -> caller_module |> List.wrap() |> embedded_data_ast(default, type) {:::, _, [module_ctx, {:none, _, _} = type]} -> caller_module |> modules(module_ctx) |> data_ast(type) {:::, _, [module_ctx, type]} -> caller_module |> modules(module_ctx) |> data_ast(default_value(type), type) {_, _, _} = type -> data_ast(caller_module, type) [do: {:__block__, _, lines}] -> data_ast(lines, __CALLER__) [do: line] -> data_ast([line], __CALLER__) end end defmacro defdata(module_ctx, do: body) do module_name = __CALLER__.module |> modules(module_ctx) |> Module.concat() inner = body |> case do {:__block__, _, lines} -> lines line -> List.wrap(line) end |> data_ast(__CALLER__) quote do defmodule unquote(module_name) do unquote(inner) end end end @doc """ Build a sum (coproduct) type from product types defmodule Light do # ============== # # Sum Definition # # ============== # defsum do defdata Red :: none() defdata Yellow :: none() defdata Green :: none() end # =================== # # Rest of Module # # (business as usual) # # =================== # def from_number(1), do: %Light.Red{} def from_number(2), do: %Light.Yellow{} def from_number(3), do: %Light.Green{} end Light.new() #=> %Light.Red{} ## Embedded Products Data with multiple fileds can be defined directly as part of a sum defmodule Pet do defsum do defdata Cat do name :: String.t() claw_sharpness :: String.t() end defdata Dog do name :: String.t() bark_loudness :: non_neg_integer() end end end ## Default Constructor The first `defdata`'s constructor will be the default constructor for the sum defmodule Maybe do defsum do defdata Nothing :: none() defdata Just :: any() end end Maybe.new() #=> %Maybe.Nothing{} ## Tagged Unions Sums join existing types with tags: new types to help distibguish the context that they are in (the sum type) defdata Book :: String.t() \\\\ "War and Peace" defdata Video :: String.t() \\\\ "2001: A Space Odyssey" defmodule Media do defsum do defdata Paper :: Book.t() defdata Film :: Video.t() \\\\ Video.new("A Clockwork Orange") end end media = Media.new() #=> %Paper{ # paper: %Book{ # book: "War and Peace" # } # } """ @spec defsum([do: {:__block__, [any()], ast()}]) :: ast() defmacro defsum(do: {:__block__, _, [first | _] = parts} = block) do module_ctx = __CALLER__.module types = or_types(parts, module_ctx) default_module = module_ctx |> List.wrap() |> Kernel.++(submodule_name(first)) |> Module.concat() quote do @type t :: unquote(types) unquote(block) @spec new() :: t() def new, do: unquote(default_module).new() defoverridable [new: 0] end end end ================================================ FILE: mix.exs ================================================ defmodule Algae.Mixfile do use Mix.Project def project do [ app: :algae, aliases: aliases(), deps: deps(), preferred_cli_env: [quality: :test], # Versions version: "1.3.1", elixir: "~> 1.9", elixirc_paths: elixirc_paths(Mix.env()), # Docs name: "Algae", docs: docs(), # Hex description: "Bootstrapped algebraic data types for Elixir", package: package() ] end defp aliases do [ quality: [ "test", "credo --strict" ] ] end defp elixirc_paths(:test), do: ["lib", "test/support"] defp elixirc_paths(_), do: ["lib"] defp deps do [ {:credo, "~> 1.5", only: [:dev, :test], runtime: false}, {:inch_ex, "~> 2.0", only: [:dev, :docs, :test], runtime: false}, {:dialyxir, "~> 1.1", only: :dev, runtime: false}, {:earmark, "~> 1.4", only: :dev, runtime: false}, {:ex_doc, "~> 0.23", only: :dev, runtime: false}, {:quark, "~> 2.2"}, {:type_class, "~> 1.2"}, {:witchcraft, "~> 1.0"}, ] end defp docs do [ extras: ["README.md"], logo: "./brand/mini-logo.png", main: "readme", source_url: "https://github.com/witchcrafters/algae" ] end defp package do [ licenses: ["Apache-2.0"], links: %{"GitHub" => "https://github.com/witchcrafters/algae"}, maintainers: ["Brooklyn Zelenka", "Steven Vandevelde"] ] end end ================================================ FILE: shell.nix ================================================ let nixpkgs = import (fetchTarball { # Run `cachix use jechol` to use compiled binary cache. url = "https://github.com/jechol/nixpkgs/archive/21.11-otp24-no-jit.tar.gz"; sha256 = "sha256:1lka707hrnkp70vny99m9fmp4a8136vl7addmpfsdvkwb81d1jk9"; }) { }; platform = if nixpkgs.stdenv.isDarwin then [ nixpkgs.darwin.apple_sdk.frameworks.CoreServices nixpkgs.darwin.apple_sdk.frameworks.Foundation ] else if nixpkgs.stdenv.isLinux then [ nixpkgs.inotify-tools ] else [ ]; in nixpkgs.mkShell { buildInputs = with nixpkgs; [ # OTP erlang elixir ] ++ platform; } ================================================ FILE: test/algae_dsl_aliasing_test.exs ================================================ defmodule AlgaeDslAliasingTest.Base do import Algae alias __MODULE__ defmodule A do defdata do a :: String.t() end end defmodule B do defdata do b :: Base.A.t() \\ Base.A.new("a for amazing!") end end defmodule C do defdata do c :: Base.B.t() end end end ================================================ FILE: test/algae_test.exs ================================================ defmodule AlgaeTest do alias Example.{Animal, Book, Media, Wrapper} use ExUnit.Case doctest Algae, import: true doctest Algae.Id, import: true doctest Algae.Maybe, import: true doctest Algae.Either, import: true doctest Algae.Free, import: true doctest Algae.Tree.BinarySearch, import: true doctest Algae.Tree.Rose, import: true doctest Algae.Reader, import: true doctest Algae.Writer, import: true doctest Algae.State, import: true test "constructor for empty type" do assert Example.Light.new() == %Example.Light.Red{} end test "constructor with one field" do assert %Example.Wrapper{} == %Wrapper{wrapper: nil} end test "constructor with multiple fields uses defaults" do crookshanks = %Animal{ name: "Crookshanks", leg_count: 4 } assert Animal.new("Crookshanks") == crookshanks end test "constructor with multiple fields can overwrite all fields" do paul = %Animal{ name: "Paul the Psychic Octopus", leg_count: 8 } assert Animal.new("Paul the Psychic Octopus", 8) == paul end test "sum constructor uses the first tagged type" do paper = %Media.Paper{ paper: %Book{ book: "War and Peace" } } assert Media.new() == paper end test "test either keeps left state using convey" do use Witchcraft r_val = Algae.Either.Right.new("right!") r_fun = Algae.Either.Right.new(fn x -> "who's there? " <> x end) l_val = Algae.Either.Left.new("left the building!!!") assert convey(r_val, r_fun) == Algae.Either.Right.new("who's there? right!") assert convey(l_val, r_fun) == l_val assert convey(l_val, l_val) == l_val assert convey(r_val, l_val) == l_val end end ================================================ FILE: test/support/example.ex ================================================ import Algae defmodule Example do @moduledoc false defdata Complex :: ([{:ok, integer()}] | number()) \\ 22 defdata Any :: any() defdata Int :: integer() defdata None :: none() defmodule Embedded.One do @moduledoc false defdata do: quux :: any() \\ 22 end defmodule Embedded.Many do @moduledoc false defdata do first :: any() second :: integer() \\ 42 end end defdata Bare do first :: any() second :: non_neg_integer() \\ 22 third :: any() end defmodule Simple do @moduledoc false defdata any() end defmodule Sum.Lights do @moduledoc false defsum do defdata Red :: any() \\ 22 defdata Yellow :: any() defdata Green :: none() end end defmodule Sum.Maybe do @moduledoc false defsum do defdata Just do value :: any() end defdata Nada :: none() end end defmodule Player do @moduledoc false # =============== # # Data Definition # # =============== # defdata do name :: String.t() hit_points :: non_neg_integer() experience :: non_neg_integer() end # =================== # # Rest of Module # # (business as usual) # # =================== # @spec attack(t(), t()) :: {t(), t()} def attack(player = %{experience: xp}, target = %{hit_points: hp}) do { %{player | experience: xp + 50}, %{target | hit_points: hp - 10} } end end defmodule Id do @moduledoc false defdata any() end defdata Wrapper :: any() defmodule Person do @moduledoc false defdata do name :: String.t() age :: non_neg_integer() end end defmodule Animal do @moduledoc false defdata do name :: String.t() leg_count :: non_neg_integer() \\ 4 end end defdata Grocery do item :: {String.t(), integer(), boolean()} \\ {"Apple", 4, false} end defmodule Constant do @moduledoc false defdata fun() def new(value), do: %Constant{constant: fn _ -> value end} end defmodule Nothing do @moduledoc false defdata none() end defmodule Light do @moduledoc false # ============== # # Sum Definition # # ============== # defsum do defdata Red :: none() defdata Yellow :: none() defdata Green :: none() end # =================== # # Rest of Module # # (business as usual) # # =================== # def from_number(1), do: %Light.Red{} def from_number(2), do: %Light.Yellow{} def from_number(3), do: %Light.Green{} end defmodule Pet do @moduledoc false defsum do defdata Cat do name :: String.t() claw_sharpness :: String.t() end defdata Dog do name :: String.t() bark_loudness :: non_neg_integer() end end end defmodule Option do @moduledoc false defsum do defdata None :: none() defdata Some :: any() end end defdata Book :: String.t() \\ "War and Peace" defdata Video :: String.t() \\ "2001: A Space Odyssey" defmodule Media do @moduledoc false defsum do defdata Paper :: Example.Book.t() \\ Example.Book.new() defdata Film :: Example.Video.t() \\ Example.Video.new("A Clockwork Orange") end end end ================================================ FILE: test/test_helper.exs ================================================ ExUnit.start()