Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
-+--
Reporter: dreixel | Owner: simonpj
Type: bug | Status: new
Priority: normal| Milestone: 7.8.1
Component: Compiler | Version: 7.5
Keywords:| Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown |Testcase:
Blockedby:|Blocking:
Related:|
-+--
Comment(by simonpj@…):
commit 984676d51291ea900cec289599e647de38645405
{{{
Author: Simon Peyton Jones simo...@microsoft.com
Date: Fri Oct 19 00:54:59 2012 +0100
Deprecate Rank2Types and PolymorphicComponents, in favour of
RankNTypes
We agreed that it's not worth the bother of trying to maintain all
these distinct flags; RankNTypes will do the job fine. Trac #6032.
compiler/main/DynFlags.hs| 11 ---
compiler/prelude/PrelRules.lhs |2 +-
compiler/simplCore/OccurAnal.lhs |2 +-
compiler/typecheck/TcMType.lhs | 13 +++--
4 files changed, 9 insertions(+), 19 deletions(-)
}}}
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:8
GHC http://www.haskell.org/ghc/
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Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type ---+ Reporter: dreixel | Owner: simonpj Type: bug | Status: closed Priority: normal| Milestone: 7.8.1 Component: Compiler |Version: 7.5 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase:| Blockedby: Blocking:|Related: ---+ Changes (by simonpj): * status: new = closed * resolution: = fixed -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: simonpj Type: bug | Status: new Priority: normal| Milestone: 7.8.1 Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Changes (by tibbe): * cc: johan.tibell@… (added) Comment: Deprecating Rank2Types would require fixing 775 modules on Hackage. That's a lot of busy work. Could we have Rank2Types just be an alias for RankNTypes? -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: simonpj Type: bug | Status: new Priority: normal| Milestone: 7.8.1 Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Comment(by simonpj): Well it'd be odd to have 2 as a ''permanent'' alias for arbitrary wouldn't it? Isn't this precisely what deprecation is for: everything works but you get a nudge saying please change when it's convenient. In fact it *is* an alias for `RankNTypes` plus a deprecation message. We can keep supporting `Rank2Types` (as an alias for `RankNTypes`), with deprecation, for multiple releases. Or what? Simon -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: simonpj Type: bug | Status: new Priority: normal| Milestone: 7.8.1 Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Comment(by illissius): Might the reason for the separation have been that type inference is in theory decidable for rank-2 types, but not higher? I'm not a type theorist but I found this for example: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.144.1202 (WRT the deprecation/aliasing proposal itself I don't have an opinion) -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: simonpj Type: bug | Status: new Priority: normal| Milestone: 7.8.1 Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Changes (by igloo): * owner: = simonpj * milestone: = 7.8.1 -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: Type: bug | Status: new Priority: normal| Milestone: Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Comment(by dreixel): I don't feel strongly about it either way. We can change `syb` to use the rank-n flag. Is there even a good reason to distinguish rank-2 from rank-n? -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: Type: bug | Status: new Priority: normal| Milestone: Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Comment(by simonpj): I don't think so. I'd be happy to see `-XRank2Types` deprecated. One less thing to deal with. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
[GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
--+-
Reporter: dreixel | Owner:
Type: bug | Status: new
Priority: normal| Component: Compiler
Version: 7.5 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby:| Blocking:
Related:|
--+-
While building syb with HEAD, Ian reported that he needed to use
RankNTypes instead of Rank2Types. I minimized the problem to:
{{{
{-# LANGUAGE Rank2Types #-}
module Rank2 where
f :: (forall a. a - (forall b. b)) - c
f = undefined
g :: (forall a b. a - b) - c
g = undefined
}}}
7.4 accepts both `f` and `g`. HEAD complains on the signature of `f`:
{{{
Illegal polymorphic or qualified type: forall b. b
Perhaps you intended to use -XRankNTypes or -XRank2Types
In the type signature for `f':
f :: (forall a. a - (forall b. b)) - c
}}}
It doesn't complain about `g`, but I think the signatures are equivalent.
Ian further reports that the change in behavior seems to have occurred
after 7.5.20120401.
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032
GHC http://www.haskell.org/ghc/
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Re: [GHC] #6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type
#6032: HEAD (7.5.20120421) requires RankNTypes for a rank-2 type -+-- Reporter: dreixel | Owner: Type: bug | Status: new Priority: normal| Milestone: Component: Compiler | Version: 7.5 Keywords:| Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown |Testcase: Blockedby:|Blocking: Related:| -+-- Changes (by simonpj): * difficulty: = Unknown Comment: The difficulty is this * The argument of a rank-2 arrow type should have rank 1 * A vanilla H98 type sig has rank 1 * But technically `(Int - forall a. a-a)` is rank 1, although it is not H98. GHC currently has the (somewhat ad-hoc) restriction that a rank-1 type must have all its foralls at the front, which is why this program is rejected. And yes that's a change in behaviour. (A different bug report said that `(Int - forall a. a-a)` was accepted despite no higher-rank flags being on. Perhaps it'd be better to always accept foralls to the right of an arrow. After all, you need at least `-XForAllTypes` to be able to write them. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/6032#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
