RE: [GHC] #2798: Enable rec keyword when RecursiveDo is enabled?
| I hope that it does but I have not installed GHC 6.12 yet. I was | wondering more how to write new programs that are not restricted to | work only with GHC = 6.12.1. Sometimes one can make things portable | with a bit of CPP---not pretty but it works---but, in this case, I | could not think of a good way to do this, so if anyone has ideas... Yes you can. Since nothing except 6.12 has 'rec', you can use 'mdo'. If you don't want the deprecation warning use -fno-warn-deprecations. Of course *any* feature removal is going to lead to programs that used to work not working any more. I don't see how to avoid that, except by keeping all features forever. We can keep mdo as long as necessary, I suppose, but I'd like some mechanism to gently encourage people to the rec syntax, which is what the deprecation warning should do. Simon ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? ---+ Reporter: nominolo | Owner: igloo Type: task | Status: closed Priority: high | Milestone: 6.14.1 Component: Compiler |Version: 6.11 Resolution: fixed | Keywords: Difficulty: Unknown | Os: Unknown/Multiple Testcase:| Architecture: Unknown/Multiple Failure: None/Unknown | ---+ Changes (by igloo): * status: new = closed * failure: = None/Unknown * resolution: = fixed Comment: It was done for 6.12.1 after all. `RecursiveDo` is deprecated in favour of `DoRec`. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:13 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] #2798: Enable rec keyword when RecursiveDo is enabled?
Hello, so with these changes, what is the preferred way to write recursive monadic code that will work on GHC 6.12.1, GHC = 6.12.1, and Hugs? I guess, one could always fall back to just using mfix directly but this seems unfortunate. -Iavor On Sun, Jan 3, 2010 at 5:23 AM, GHC t...@galois.com wrote: #2798: Enable rec keyword when RecursiveDo is enabled? ---+ Reporter: nominolo | Owner: igloo Type: task | Status: closed Priority: high | Milestone: 6.14.1 Component: Compiler | Version: 6.11 Resolution: fixed | Keywords: Difficulty: Unknown | Os: Unknown/Multiple Testcase: | Architecture: Unknown/Multiple Failure: None/Unknown | ---+ Changes (by igloo): * status: new = closed * failure: = None/Unknown * resolution: = fixed Comment: It was done for 6.12.1 after all. `RecursiveDo` is deprecated in favour of `DoRec`. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:13 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 ___ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
Re: [GHC] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: igloo Type: task | Status: new Priority: high |Milestone: 6.14.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Changes (by igloo): * milestone: 6.12.1 = 6.14.1 Comment: Won't be done in time for 6.12.1. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:12 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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: igloo Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Changes (by igloo): * owner: = igloo -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:11 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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Comment (by igloo): Extensions can be marked deprecated in `xFlags` in `compiler/main/DynFlags.hs`. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:10 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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Comment (by simonmar): We (Simon Simon) think the ideal state of affairs would be: * Allow `rec` in `do` (as Ross intended) * Deprecate `mdo` as far as flags go, there are two options: * have the existing `RecursiveDo` flag enable the new `rec` syntax, and deprecate the use of `mdo`. Eventually `mdo` would be removed as a keyword. * Define a new extension, e.g. `DoRec` for the new `rec` keyword, and deprecate the old `RecursiveDo` extension. The second approach has the benefit that we can identify obsolete code on Hackage without trying to compile it, but it means having two similarly- named extensions which could lead to confusion. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Comment (by duncan): I don't think I'd bother with changing the extension name. We can discover deprecated stuff on hackage automatically by other (more general) means. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Comment (by isaacdupree): my feeling is to prefer `DoRec` -- it sounds more mnemonic to me; and it seems unpleasant for an extension to have two substantially different parsings that might conflict with existing code (if 'rec' is a variable name somewhere). e.g. how will haskell-src[-exts] deal with it after the Summer-of-Code effort? But I don't really mind either way. (P.S. do we have a way to mark extension-flags deprecated?) -Isaac -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:8 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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Comment (by isaacdupree): so if you want your code to compile on pre-6.12 you can: - just use `mdo` - use `rec` and enable `Arrows` also (I guess this hack could be, but shouldn't be, sanctioned by Cabal.. among other things, Arrows also introduces `proc` as a keyword, so it's not harmless) -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: high |Milestone: 6.12.1 Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Changes (by igloo): * priority: normal = high * milestone: 6.12 branch = 6.12.1 Comment: 6.12.1 would be a good time to come to a decision about this. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: normal|Milestone: 6.12 branch Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Difficulty: Unknown Testcase:| Os: Unknown/Multiple Architecture: Unknown/Multiple | -+-- Changes (by igloo): * milestone: = 6.12 branch -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled?
--+-
Reporter: nominolo | Owner:
Type: task | Status: new
Priority: normal| Milestone:
Component: Compiler |Version: 6.11
Severity: minor | Resolution:
Keywords:| Difficulty: Unknown
Testcase:| Architecture: Unknown/Multiple
Os: Unknown/Multiple |
--+-
Changes (by simonpj):
* difficulty: = Unknown
Comment:
I think the reason for 'mdo' was by analogy with 'let' and 'where': just
say use recursion and let the compiler sort out the details. I have
forgotten whether the same choice could be made for arrows, or whether
'rec' is essential there.
I don't feel strongly about this. I suppose we could do any of these:
* Remove 'rec' altogether (including from arrows i.e. 'proc')
* Remove 'mdo' and use 'do rec' instead
* Allow 'rec' in 'do' as well as in 'proc'
* Status quo ('rec' in 'proc' but not in 'do')
Simon
--
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#comment:2
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Re: [GHC] #2798: Enable rec keyword when RecursiveDo is enabled?
#2798: Enable rec keyword when RecursiveDo is enabled? -+-- Reporter: nominolo |Owner: Type: task | Status: new Priority: normal|Milestone: Component: Compiler | Version: 6.11 Severity: minor | Resolution: Keywords:| Testcase: Architecture: Unknown/Multiple | Os: Unknown/Multiple -+-- Comment (by ross): The idea of rec was to use it with plain do, to indicate feedback explicitly as an alternative to using mdo. Many users of arrow notation prefer to do that. As you say, it's not much use together with mdo. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/2798#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
