Proposal: Dot as Postfix Function Apply

[Andrew Gibiansky]

I'm not on either side of this fence yet, but keep in mind that this can't
just be done with an operator, because, if I understand the proposal
correctly, the proposed dot hack would have a precedence *higher* than
function application.

That is, code like

print person.name

would desugar to

print (name person)

and not to

name (print person)

This is something that can't be replicated with current Haskell and is the
crux of the issue, I think.

As Chris Done said, "All of this because Haskellers are allergic to
parentheses." (A true comment, if perhaps one I maybe don't agree with)

-- Andrew

On Wed, Nov 4, 2015 at 10:28 AM, Andrew Farmer <anfarmer at fb.com> wrote:

> I'm a strong -1. This already exists as an operator anyway:
>
> http://hackage.haskell.org/package/lens-4.13/docs/Control-Lens-Operators.ht
> ml#v:-38-
>
>
> On 11/4/15, 6:16 AM, "Libraries on behalf of Dominique Devriese"
> <libraries-bounces at haskell.org on behalf of
> dominique.devriese at cs.kuleuven.be> wrote:
>
> >+1
> >
> >I'm convinced that this proposed extension would be extremely natural
> >and practical if we give it a chance.  The fact that it may conflict
> >with previous, less natural syntax choices (lens composition with .
> >comes to mind) should not be counted against an opt-in extension.
> >Lens packages could easily provide an alternative notation for their .
> >for when the extension is enabled.
> >
> >Regards,
> >Dominique
> >
> >2015-11-04 11:44 GMT+01:00 Jeremy <voldermort at hotmail.com>:
> >> Dot as Postfix Function Apply
> >>
> >>(
> https://urldefense.proofpoint.com/v2/url?u=https-3A__ghc.haskell.org_tra
> >>c_ghc_wiki_Records_DeclaredOverloadedRecordFields_DotPostfix&d=CwICAg&c=5
> >>VD0RTtNlTh3ycd41b3MUw&r=jwmD0T3rI1L_0LSiPtRSfw&m=YDwguWCVjHH3yABXsya8ZZnG
> >>xAokec8hTZyMcwu8voE&s=ZxiyXvL6jUpla8Ikbdndqpoft7zJnvOGqHgicaQBP2I&e= )
> >> was originally part of ORF, but dropped to keep the scope/discussion
> >>more
> >> manageable. Now that ORF is in for GHC 8.0, I would like to re-propose
> >>dot
> >> postfix syntax.
> >>
> >> The idea is that instead of
> >>
> >> (title person) ++ " " ++ (firstName person) ++ " " ++ (lastName person)
> >>
> >> we could have
> >>
> >> person.title ++ " " ++ person.firstName ++ " " ++ person.lastName
> >>
> >> This is a simple source-to-source translation with no changes to the
> >>type
> >> system (TDNR is an orthogonal proposal). The advantages are:
> >>
> >>   1. Code that's easier to read/write.
> >>   2. Familiar to users of almost every other programming language.
> >>   3. IDE auto-complete - an IDE can suggest functions applicable to the
> >> variable after typing .
> >>
> >> This would be an opt-in extension.
> >>
> >> I'm posting this to the libraries list because that's where proposals
> >> generally go, although this isn't strictly a library issue. If it
> >>should be
> >> on a different list I'll move it.
> >>
> >>
> >>
> >> --
> >> View this message in context:
> >>
> https://urldefense.proofpoint.com/v2/url?u=http-3A__haskell.1045720.n5.na
> >>bble.com_Proposal-2DDot-2Das-2DPostfix-2DFunction-2DApply-2Dtp5821620.htm
> >>l&d=CwICAg&c=5VD0RTtNlTh3ycd41b3MUw&r=jwmD0T3rI1L_0LSiPtRSfw&m=YDwguWCVjH
> >>H3yABXsya8ZZnGxAokec8hTZyMcwu8voE&s=L_6yc68pNbnhlMLCkcHBSU8qXF8vWd69dLL7W
> >>70W4uY&e=
> >> Sent from the Haskell - Libraries mailing list archive at Nabble.com.
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