Weird pattern matching bug

[trizko]

Both of these functions compile without errors:

toAction : Int -> Action
toAction x =
  case x of
    -1 -> Left
    1  -> Right
    _  -> NoOp

toAction : Int -> Action
toAction x =
  case x of
    1  -> Right
    (-1) -> Left
    _  -> NoOp

However, when I try to compile this code(using elm-reactor or elm-make initial-code/Spaceship.elm --output test.js):

toAction : Int -> Action
toAction x =
  case x of
    1  -> Right
    -1 -> Left
    _  -> NoOp

I get the following error:

Detected errors in 1 module.
-- SYNTAX PROBLEM ----------------------------------- initial-code/Spaceship.elm

I ran into something unexpected when parsing your code!

88│     -1 -> Left
           ^
I am looking for one of the following things:

    end of input
    whitespace

elm-package.json:

...
    "dependencies": {
        "elm-lang/core": "3.0.0 <= v < 4.0.0",
        "evancz/elm-html": "4.0.2 <= v < 5.0.0",
        "evancz/start-app": "2.0.2 <= v < 3.0.0"
    },
    "elm-version": "0.16.0 <= v < 0.17.0"
...

environment:

$ brew cask info elm-platform
elm-platform: 0.16
Elm
http://www.elm-lang.org
/opt/homebrew-cask/Caskroom/elm-platform/0.16 (23M)
https://github.com/caskroom/homebrew-cask/blob/master/Casks/elm-platform.rb
==> Contents
  Elm-Platform-0.16.pkg (pkg)

[trizko]

Closing cause @rtfeldman just does it better than me in #1261 lol

[rtfeldman]

Thanks for discovering it! 😸