Re: [Diffusion] [Committed] rCABAL2863a628f857: Add two local type signatures

No, this is a Phabricator bug due to some changes in how commit imports are handled. I just upgraded earlier; I'm tracking it down now. At minimum, I'll find a way to turn off the email spam. On Fri, Jul 8, 2016 at 2:46 PM, Simon Peyton Jones via ghc-devs < ghc-devs@haskell.org> wrote:

I don’t believe I made this commit, or the ones around it. Mysterious; I hope I’m not being impersonated!

Simon

*From:* noreply@phabricator.haskell.org [mailto: noreply@phabricator.haskell.org] *Sent:* 08 July 2016 20:43 *To:* Simon Peyton Jones *Subject:* [Diffusion] [Committed] rCABAL2863a628f857: Add two local type signatures

simonpj committed rCABAL2863a628f857: Add two local type signatures (authored by simonpj).

Add two local type signatures

I'm adding these type signatures to satisfy the "do not generalise local let/where" rule that GHC is taking on.

The signatures are clearly correct, but I was surprised at the polymorphism needed. For example

parseOptVersion :: ReadP r Version parseOptVersion = parseQuoted ver <++ ver

where ver :: ReadP r Version

ver = parse <++ return noVersion

noVersion = Version{ versionBranch=[], versionTags=[] }

Note that 'ver' really is called at two different types! That in turn is because of the type of (<++)

(<++) :: ReadP a a -> ReadP r a -> ReadP r a

(+++) :: ReadP r a -> ReadP r a -> ReadP r a

Note the "a a" in the first arg, which is very unusual. For example, compare the type of (+++).

Changing it to match the type of (+++) makes ReadP fail to compile, though, so I assume it's right as it stands. But surely this deserves a comment?!

*AFFECTED FILES*

/Distribution/ParseUtils.hs

*USERS*

simonpj (Author)

*COMMIT*

https://phabricator.haskell.org/rCABAL2863a628f857

*EMAIL PREFERENCES*

https://phabricator.haskell.org/settings/panel/emailpreferences/

*To: *simonpj

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