elm-xref

Cross-referencing tools for Elm. Find unused code, and figure out where specific functions are used.

Installation

npm i -g elm-xref

Usage

To index a project and find unused functions, execute elm-xref in the same directory as your elm.json. This works for both application as well as package projects.

To find usages of a function, specify the fully qualified function name as an argument.

Examples on rtfeldman/elm-spa-example@c8c3201:

# To find unused functions:
$ elm-xref
Unused functions:
 - /Users/ilias/Src/elm/elm-spa-example/src/Api.elm:294:1       Api.cacheStorageKey
 - /Users/ilias/Src/elm/elm-spa-example/src/Api.elm:299:1       Api.credStorageKey
 - /Users/ilias/Src/elm/elm-spa-example/src/Api.elm:73:1        Api.decode
 - /Users/ilias/Src/elm/elm-spa-example/src/Author.elm:120:1    Author.follow
 - /Users/ilias/Src/elm/elm-spa-example/src/Author.elm:125:1    Author.unfollow
 - /Users/ilias/Src/elm/elm-spa-example/src/Avatar.elm:55:1     Avatar.toMaybeString
 - /Users/ilias/Src/elm/elm-spa-example/src/Email.elm:30:7      Email.Email
 - /Users/ilias/Src/elm/elm-spa-example/src/Email.elm:44:1      Email.decoder
 - /Users/ilias/Src/elm/elm-spa-example/src/Email.elm:39:1      Email.encode
 - /Users/ilias/Src/elm/elm-spa-example/src/Email.elm:34:1      Email.toString
 - /Users/ilias/Src/elm/elm-spa-example/src/Main.elm:112:7      Main.ChangedRoute
 - /Users/ilias/Src/elm/elm-spa-example/src/Page.elm:26:7       Page.Login
 - /Users/ilias/Src/elm/elm-spa-example/src/Page.elm:27:7       Page.Register
 - /Users/ilias/Src/elm/elm-spa-example/src/Page.elm:28:7       Page.Settings
 - /Users/ilias/Src/elm/elm-spa-example/src/Page/Settings.elm:90:7      Page.Settings.Valid
 - /Users/ilias/Src/elm/elm-spa-example/src/Page/Settings.elm:456:1     Page.Settings.nothingIfEmpty
 - /Users/ilias/Src/elm/elm-spa-example/src/Route.elm:19:7      Route.Root

# To find usages of `Maybe.Just`:
$ elm-xref Maybe.Just
Usages:
 - Api.storeCredWith (113)
 - Article.faveDecoder (231)
 - Article.favorite (221)
 - Article.Comment.post (80, 81)
 - Article.Slug.urlParser (22)
 - Author.followDecoder (145)
 - Author.requestFollow (132)
 - Main.changeRouteTo (179)
 - Page.Article.Editor.create (535, 536)
 - Page.Article.Editor.edit (560)
 - Page.Article.Editor.getSlug (583, 586, 589, 592, 595)
 - Page.Settings.nothingIfEmpty (462)
 - Session.cred (42)
 - Session.viewer (32)
 - Username.urlParser (43)

Value constructors of types are also tracked. Note that only constructing values is tracked as usage - pattern matches and destructuring are not tracked as usage.

Usage tracking isn't terribly clever. This tool only does static analysis and does not attempt to evaluate any expressions. As a result, functions that only appear in "obviously unreachable code" (i.e. conditionals that always evaluate to False) do very much count as usage.

Roadmap

• Support whitelisting (f.e. with phantom types or internal modules with consistent API)
• Show unused parameters
• Support type aliases (as function and in type signatures)

License

See the LICENSE file.