Re: pattern signatures

Or maybe "pattern ascription"? "type-ascription" is implied as "ascription" isn't commonly used for something else (AFAIK). Sylvain On 08/01/2018 13:59, Simon Peyton Jones via ghc-devs wrote:

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

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