[Haskell-cafe] GHC Extension Proposal: ArgumentBlock

[Kyle Marek-Spartz]

Not sure about that. $ isn't syntax. It's defined in terms of the
language.

($) :: (a -> b) -> a -> b
f $ x =  f x

If we didn't have the $ operator, we'd make it ourselves.


Alexey Vagarenko writes:

> Consider this.
> If we didn't have $ operator in the first place, we'd use parentheses
> everywhere:
>
>     foo (bar (baz (qux (quux (do a <- b; return a)))))
> under your proposal it turns to:
>     foo (bar (baz (qux (quux do a <- b; return a))))
>
> another example:
>     foo (bar baz) (qux quux) (do a <- b; return a)
> turns to :
>     foo (bar baz) (qux quux) do a <- b; return a
>
> with lambdas:
>     foo (bar baz) (qux quux) (\x -> x)
> to:
>     foo (bar baz) (qux quux) \x -> x
>
> Can't you see your proposal makes things *less *consistent, *not more*?
> -1.
>
> 2015-09-07 0:03 GMT+06:00 Oliver Charles <ollie at ocharles.org.uk>:
>
>> I mean that people us $ for purely syntactical purposes. If an editor is
>> going to make refactorings and retain a certain sense of style, then the
>> tool needs to know that $ is sometimes to be used. The refactoring (or
>> otherwise) tool now has to be aware of the syntax of Haskell and special
>> symbols in the Prelude.
>>
>> On Sun, Sep 6, 2015 at 6:53 PM Matthew Pickering <
>> matthewtpickering at gmail.com> wrote:
>>
>>> >
>>> > I don't really like $ from an editor perspective though (tooling has to
>>> > become aware of a single function when performing refactorings), so
>>> anything
>>> > that helps reduce how prolific that operator is is a win in my book!
>>> >
>>>
>>> Can you please explain what you mean by this? Is there something more
>>> subtle that $ being a low fixity operator? Which specific problems
>>> does it cause tooling? Are you referring to the fact that there are
>>> problems because $ == id and makes tooling account for two cases when
>>> looking for refactorings? (I'm thinking of hlint here).
>>>
>>> (FWIW, haskell-src-exts tries to fiddle with the AST to account for
>>> fixity after parsing but the GHC parser does not, it happens during
>>> renaming. There is a pure version here[1] if anyone else is in need of
>>> this feature).
>>>
>>> Thanks, Matt
>>>
>>
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--
Kyle Marek-Spartz