{"id":17250936,"url":"https://github.com/sjoerdvisscher/effects","last_synced_at":"2026-03-07T03:31:08.091Z","repository":{"id":62435882,"uuid":"2583258","full_name":"sjoerdvisscher/effects","owner":"sjoerdvisscher","description":"Control.Effects","archived":false,"fork":false,"pushed_at":"2019-04-14T14:38:14.000Z","size":30,"stargazers_count":19,"open_issues_count":0,"forks_count":0,"subscribers_count":3,"default_branch":"master","last_synced_at":"2025-12-07T23:44:14.800Z","etag":null,"topics":["eff","haskell","monad-transformers"],"latest_commit_sha":null,"homepage":"http://hackage.haskell.org/package/effects","language":"Haskell","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"bsd-3-clause","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/sjoerdvisscher.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null}},"created_at":"2011-10-15T19:51:45.000Z","updated_at":"2021-08-23T20:09:03.000Z","dependencies_parsed_at":"2022-11-01T21:32:29.565Z","dependency_job_id":null,"html_url":"https://github.com/sjoerdvisscher/effects","commit_stats":null,"previous_names":[],"tags_count":1,"template":false,"template_full_name":null,"purl":"pkg:github/sjoerdvisscher/effects","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/sjoerdvisscher%2Feffects","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/sjoerdvisscher%2Feffects/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/sjoerdvisscher%2Feffects/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/sjoerdvisscher%2Feffects/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/sjoerdvisscher","download_url":"https://codeload.github.com/sjoerdvisscher/effects/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/sjoerdvisscher%2Feffects/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":30206563,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-03-07T03:24:23.086Z","status":"ssl_error","status_checked_at":"2026-03-07T03:23:11.444Z","response_time":53,"last_error":"SSL_connect returned=1 errno=0 peeraddr=140.82.121.6:443 state=error: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"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":["eff","haskell","monad-transformers"],"created_at":"2024-10-15T06:49:55.475Z","updated_at":"2026-03-07T03:31:08.047Z","avatar_url":"https://github.com/sjoerdvisscher.png","language":"Haskell","funding_links":[],"categories":[],"sub_categories":[],"readme":"Control.Effects\n===============\n\nControl.Effects is a Haskell library for programming with effects, like in the the [Eff language][Eff] by Andrej Bauer and Matija Pretnar. Effects can be used instead of monad transformers, they are designed to be easier to use and to define.\n\nInstallation\n------------\n\n    cabal install effects\n\nUsing effects\n-------------\n\nHere's an example how to use the state effect from `Control.Effects.State`.\n\n    example :: (Int, Int)\n    example = run $ do\n      with (ref 5) $ \\x -\u003e do\n        with (ref 10) $ \\y -\u003e do\n          x =: (+) \u003c$\u003e get x \u003c*\u003e get y\n          y =: (+) \u003c$\u003e get x \u003c*\u003e get y\n          (,) \u003c$\u003e get x \u003c*\u003e get y\n\nEvery instance of an effect is given a name (`x` and `y` in this example), which makes is possible to easily mix several instances of the same effect.\n\nFor more examples see [examples.hs](https://github.com/sjoerdvisscher/effects/blob/master/examples.hs). \nAnother good example is the implementation of a [parser](https://github.com/nybble41/effects-parser) by Jesse McDonald.\n\n[Eff]: http://math.andrej.com/category/programming/eff/?category_name=programming/eff\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fsjoerdvisscher%2Feffects","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fsjoerdvisscher%2Feffects","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fsjoerdvisscher%2Feffects/lists"}