Comment by pyrale | Hacker News Reader

Comment by pyrale | Hacker News Reader

Parent Full thread

> indentation preferences are strictly enforced. It's basically taken an awkward edge-case from Haskell's indentation rules and made it not only a requirement, but a prerequisite to seeing if there are any other errors in your program.

Some parsing is less efficient than Haskell because Elm doesn't have 20+ years of PhDs working on it, but there is no such thing as compiler-enforced formatting. I can't think of compiler errors regarding format that are the expression of a choice, as you put it, rather than the expression of less manpower.

Likewise, `where` clauses aren't forbidden, they are simply not implemented, which, given that you can already use `let.. in`, is not especially shocking.

The omission of where clauses was explicitly a stylistic choice[1].

This is perfectly valid Haskell:

    #!/usr/bin/env stack
    {- stack script --resolver lts-12.19 -}
    data Test = Test {count :: Int}
    
    test = let
      something = Test {
        count = 5
      }
      in 5+(count something)
    
    main = putStrLn $ show test

To get the equivalent Elm to compile, it must be indented like this:

    test = let
               something = {
                 count = 5
                 }
      in 5+(something.count)

Note that `something` must be indented beyond the beginning of `let`, and the closing curly brace must be indented to the same level as `count`. These are both not a warning, but a parse error - you can confirm it with Ellie[2]. If that were due to a lack of resources, it would absolutely be understandable, but this also was an explicit choice[3] which developer time was spent implementing.

[1] https://github.com/elm/compiler/issues/621

[2] https://ellie-app.com/5KRg4g5ZMkba1

[3] https://github.com/elm/compiler/issues/1573

Reply on news.ycombinator.com