Further complicated by the fact that that form used to be called a "pattern signature" with accompanying extension, until that was folded into ScopedTypeVariables extension. On Fri, Jan 5, 2018 at 9:41 AM, Simon Peyton Jones via ghc-devs < ghc-devs@haskell.org> wrote:

Ah yes. I think we started with "pattern synonym signature" for (b) but have since denenerated to "pattern signature" which is quite confusing.

User advice would be good!

S

| -----Original Message----- | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of | Richard Eisenberg | Sent: 05 January 2018 13:48 | To: GHC | Subject: pattern signatures | | Hi devs, | | Is a pattern signature | | a) something you put after `pattern P ::` ? | b) something you put after `::` in a pattern, as in `foo (Proxy :: | Proxy a)` ? | | I've seen the term "pattern signature" apply to both, and I've been | tripped up by this. Does anyone have terminology that unambiguously | separates these two constructs that we can all adopt? | | Thanks! | Richard | _______________________________________________ | ghc-devs mailing list | ghc-devs@haskell.org | https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.h | askell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc- | devs&data=02%7C01%7Csimonpj%40microsoft.com%7Cbc86346cc90f4a9516d108d5 | 5442f5a0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C6365075689386605 | 89&sdata=gvjnHyGAojz982UEV1u0hZPKH%2B%2F3UjiDlQm10%2BRZ7r8%3D&reserved | =0 _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

Well, as you say, "pattern signature" makes sense for both, so I would expect to use context to disambiguate. If I wanted to be explicit about which one I meant, I'd use: a) "Pattern synonym signature" b) "Signature on a pattern" -Iavor On Fri, Jan 5, 2018 at 1:12 PM Joachim Breitner wrote:

Hi,

Am Freitag, den 05.01.2018, 13:42 -0500 schrieb Brandon Allbery:

...

Further complicated by the fact that that form used to be called a "pattern signature" with accompanying extension, until that was folded into ScopedTypeVariables extension.

which I find super confusing, because sometimes I want a signature on a pattern and it is counter-intuitive to me why I should not longer use the obviously named PatternSignatures extension but rather the at first glance unrelated ScopedTypeVariable extension.

But I am derailing the discussion a bit.

Cheers, Joachim

-- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/ _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

I like the idea of distinguishing “signatures” from “annotations”. But then what is currently a “pattern signature” with extension -XPatternSignatures, becomes “type annotation in a pattern” or perhaps “pattern type-annotation” which is a bit clumsy. Possibly “type specification” instead of “type annotation”. Thus “pattern type-spec” which is snappier. Simon From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Spiwack, Arnaud Sent: 08 January 2018 10:11 Cc: Joachim Breitner ; ghc-devs@haskell.org Subject: Re: pattern signatures In my eyes, signatures are something which goes with a definition. So (a) is a pattern (synonym) signature, while (b) is merely a type annotation on a pattern. On Fri, Jan 5, 2018 at 11:23 PM, Iavor Diatchki mailto:iavor.diatchki@gmail.com> wrote: Well, as you say, "pattern signature" makes sense for both, so I would expect to use context to disambiguate. If I wanted to be explicit about which one I meant, I'd use: a) "Pattern synonym signature" b) "Signature on a pattern" -Iavor On Fri, Jan 5, 2018 at 1:12 PM Joachim Breitner mailto:mail@joachim-breitner.de> wrote: Hi, Am Freitag, den 05.01.2018, 13:42 -0500 schrieb Brandon Allbery:

Further complicated by the fact that that form used to be called a "pattern signature" with accompanying extension, until that was folded into ScopedTypeVariables extension.

which I find super confusing, because sometimes I want a signature on a pattern and it is counter-intuitive to me why I should not longer use the obviously named PatternSignatures extension but rather the at first glance unrelated ScopedTypeVariable extension. But I am derailing the discussion a bit. Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.demailto:mail@joachim-breitner.de http://www.joachim-breitner.de/https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.joachim-breitner.de%2F&data=02%7C01%7Csimonpj%40microsoft.com%7Ccca9ff6f4b2b4a32e61308d55680514e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636510031494207475&sdata=%2BWGJXq6S7IrWJzsYIZWdk%2BDa%2BSLtW8CfCiPHitgnArc%3D&reserved=0 _______________________________________________ ghc-devs mailing list ghc-devs@haskell.orgmailto:ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devshttps://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.haskell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-devs&data=02%7C01%7Csimonpj%40microsoft.com%7Ccca9ff6f4b2b4a32e61308d55680514e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636510031494207475&sdata=L7reldRrJzSuxRhDTFUgNoy8zXHEbW96rqY8TpUeHxI%3D&reserved=0 _______________________________________________ ghc-devs mailing list ghc-devs@haskell.orgmailto:ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devshttps://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.haskell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc-devs&data=02%7C01%7Csimonpj%40microsoft.com%7Ccca9ff6f4b2b4a32e61308d55680514e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636510031494207475&sdata=L7reldRrJzSuxRhDTFUgNoy8zXHEbW96rqY8TpUeHxI%3D&reserved=0