On Mar 21, 2018, at 2:25 PM, Joachim Breitner wrote:

How about we special case the syntax

:type _ :: Foo

I really liked this for a moment, but then I realized it doesn't work if you want to reduce a type that isn't of kind Type. But maybe you're onto something here. What about having the following set of options for :type: 1. +v means to print the type of the thing exactly as-is, without any funny business 2. +d means to default the type 3. +t means that you're asking for the type of a type, instead of the type of an expression 4. +f means to evaluate any type families 5. +s means to expand any type synonyms +v is incompatible with +d, +f, and +s. Otherwise, I think these mix nicely. :kind becomes a synonym for :type +t and :kind! becomes a synonym for :type +t +f. Note that users can define their own synonyms through :def. Richard

Ok, so it looks like we should bounce this back to the author to improve the syntax and address Richard’s comment. This what I will do unless I hear otherwise by the end of the week. Cheers, Manuel

Am 22.03.2018 um 23:26 schrieb Simon Peyton Jones :

Like Richard

* I like the goal * I hate the proposed command :kind!

I suppose we could add :eval <expression> as a way to evaluate <expression>; a long-form of <expression> and then :eval type <type> for this proposal.

Simon

| -----Original Message----- | From: ghc-steering-committee On Behalf Of Manuel M T Chakravarty | Sent: 21 March 2018 02:43 | To: ghc-steering-committee@haskell.org | Subject: [ghc-steering-committee] Proposal #79 "Add a :kind!! command | to ghci" — propose yes | | We need to decide on the Proposal #79 ”Add a :kind!! command to ghci, | to expand type families and type synonyms”: | | (rendered) | https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithu | b.com%2Falpmestan%2Fghc-proposals%2Fblob%2Fmaster%2Fproposals%2F0000- | kind-bang- | bang.rst&data=04%7C01%7Csimonpj%40microsoft.com%7Cc5767d25630244346d5a | 08d58ed5770e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636571969830 | 865127%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJ | BTiI6Ik1haWwifQ%3D%3D%7C- | 1&sdata=TiBF9Hg1BxieAB2B6Naez9FWiX53Hhfg0BP%2B%2F3MKjHs%3D&reserved=0 | (discussion) | https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithu | b.com%2Fghc-proposals%2Fghc- | proposals%2Fpull%2F79&data=04%7C01%7Csimonpj%40microsoft.com%7Cc5767d2 | 5630244346d5a08d58ed5770e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7 | C636571969830865127%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIj | oiV2luMzIiLCJBTiI6Ik1haWwifQ%3D%3D%7C- | 1&sdata=VhEDSDfQQM19L3sY1yyuT5cHJ24jroBSdVg19DVWZiE%3D&reserved=0 | | I agree that this is useful functionality and it is a simple change to | GHCi. There has been some discussion about the naming of this command, | but TBH I didn’t find any of the alternatives more convincing than | ”:kind!!”, so I’d suggest to stick with that. | | I favour accepting this proposal. Are there any dissenting opinions? | | Cheers, | Manuel | | _______________________________________________ | ghc-steering-committee mailing list | ghc-steering-committee@haskell.org | https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering- | committee