{"id":17130702,"url":"https://github.com/jechol/defr","last_synced_at":"2025-12-11T23:47:37.995Z","repository":{"id":39874366,"uuid":"390963796","full_name":"jechol/defr","owner":"jechol","description":"defr is def for Witchcraft's Reader monads.","archived":false,"fork":false,"pushed_at":"2024-05-02T21:15:49.000Z","size":298,"stargazers_count":4,"open_issues_count":8,"forks_count":0,"subscribers_count":1,"default_branch":"master","last_synced_at":"2025-10-10T19:36:26.725Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":"","language":"Elixir","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"other","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/jechol.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE.md","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2021-07-30T06:55:32.000Z","updated_at":"2022-01-03T05:56:55.000Z","dependencies_parsed_at":"2023-07-13T08:28:12.535Z","dependency_job_id":"d271aa29-3da6-4e5c-bf74-46b7773d0c79","html_url":"https://github.com/jechol/defr","commit_stats":null,"previous_names":["trevorite/defr"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/jechol/defr","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/jechol%2Fdefr","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/jechol%2Fdefr/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/jechol%2Fdefr/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/jechol%2Fdefr/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/jechol","download_url":"https://codeload.github.com/jechol/defr/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/jechol%2Fdefr/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":279097350,"owners_count":26102790,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","status":"online","status_checked_at":"2025-10-15T02:00:07.814Z","response_time":56,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":[],"created_at":"2024-10-14T19:13:00.478Z","updated_at":"2025-10-15T17:49:44.248Z","avatar_url":"https://github.com/jechol.png","language":"Elixir","funding_links":[],"categories":[],"sub_categories":[],"readme":"[![mix test](https://github.com/trevorite/defr/workflows/mix%20test/badge.svg)](https://github.com/trevorite/defr/actions)\n[![Hex version badge](https://img.shields.io/hexpm/v/defr.svg)](https://hex.pm/packages/defr)\n[![License badge](https://img.shields.io/hexpm/l/defr.svg)](https://github.com/trevorite/defr/blob/master/LICENSE.md)\n\n`defr` is `def` for Witchcraft's Reader monads.\n\n## Installation\n\nThe package can be installed by adding `defr` to your list of dependencies\nin `mix.exs`:\n\n```elixir\ndef deps do\n  [{:defr, \"~\u003e 0.3\"}]\nend\n```\n\nTo format `defr` like `def`, add following to your `.formatter.exs`\n\n```elixir\nlocals_without_parens: [defr: 2]\n```\n\n## `defr` transformation\n\n```elixir\ndefmodule Target do\n  use Defr\n\n  import Enum, only: [at: 2]\n\n  defr top(list) do\n    list |\u003e List.flatten() |\u003e inject() |\u003e middle() |\u003e run()\n  end\n\n  defr middle(list) do\n    list |\u003e bottom() |\u003e inject() |\u003e run()\n  end\n\n  defrp bottom(list) do\n    %{pos: pos} \u003c- ask()\n    let _ = Process.sleep(100) # Use `let` to call non-reader function.\n    list |\u003e at(pos) |\u003e inject()\n  end\nend\n```\n\nbecomes (simplified for clarity)\n\n```elixir\ndefmodule Target do\n  def top(list)  do\n    monad(%Algae.Reader{}) do\n      env \u003c- Algae.Reader.ask()\n      return(\n        list\n        |\u003e Map.get(env, \u0026List.flatten/1, \u0026List.flatten/1).()\n        |\u003e middle()\n        |\u003e Reader.run(env)\n      )\n    end\n  end\n\n  def middle(list) do\n    monad %Algae.Reader{}  do\n      env \u003c- Algae.Reader.ask()\n      let _ = Process.sleep(100)\n      return(\n        list\n        |\u003e Map.get(env, \u0026Target.bottom/1, \u0026Target.bottom/1).()\n        |\u003e Reader.run(env)\n      )\n    end\n  end\n\n  defp bottom(list) do\n    monad %Algae.Reader{} do\n      env \u003c- Algae.Reader.ask()\n      %{pos: pos} \u003c- Algae.Reader.ask()\n      return(\n        list\n        |\u003e Map.get(env, \u0026Enum.at/2, \u0026Enum.at/2).(pos)\n      )\n    end\n  end\nend\n```\n\n## Test\n\n```elixir\ntest \"defr\" do\n  assert 1 == Target.top([[0], 1]) |\u003e Reader.run(%{pos: 1})\n\n  assert 20 ==\n            Target.top([[0], 1]) |\u003e Reader.run(mock(%{\u0026List.flatten/1 =\u003e [10, 20, 30], pos: 1}))\n\n  assert :imported_func ==\n            Target.top([[0], 1]) |\u003e Reader.run(mock(%{\u0026Enum.at/2 =\u003e :imported_func, pos: 1}))\n\n  assert :private_func ==\n            Target.top([[0], 1])\n            |\u003e Reader.run(mock(%{\u0026Target.bottom/1 =\u003e :private_func}))\nend\n```\n\n## License\n\nThis project is licensed under the MIT License - see the [LICENSE](LICENSE.md) file for details\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fjechol%2Fdefr","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fjechol%2Fdefr","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fjechol%2Fdefr/lists"}