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GHC | 1 Jul 2009 01:22
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by duncan):

 I dislike the asymmetry. The ++ operator is not commutative but we don't
 artificially make it visually asymmetric. Why not take Ross's proposal and
 use <> as in Data.Sequence.

 For the sake of the discussion, perhaps someone should also explain why we
 cannot just generalise the type of ++. There's a separate argument that we
 should not.

 Also, what is the purpose of the flipped append? Why do we want to
 dedicate a symbol for flipped append? I use monoid operations a lot and I
 cannot think of a single use of flipped append.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3339#comment:1>
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GHC | 1 Jul 2009 04:30
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Re: [GHC] #3012: A little deriving for GADTs

#3012: A little deriving for GADTs
---------------------------------+------------------------------------------
    Reporter:  guest             |        Owner:                  
        Type:  feature request   |       Status:  new             
    Priority:  normal            |    Milestone:  6.12.1          
   Component:  Compiler          |      Version:  6.10.1          
    Severity:  minor             |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
---------------------------------+------------------------------------------
Changes (by FSalad):

 * cc: daniels <at> community.haskell.org (added)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3012#comment:4>
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GHC | 1 Jul 2009 04:39
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Re: [GHC] #3012: A little deriving for GADTs

#3012: A little deriving for GADTs
---------------------------------+------------------------------------------
    Reporter:  guest             |        Owner:                  
        Type:  feature request   |       Status:  new             
    Priority:  normal            |    Milestone:  6.12.1          
   Component:  Compiler          |      Version:  6.10.1          
    Severity:  minor             |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
---------------------------------+------------------------------------------
Comment (by FSalad):

 Replying to [comment:1 simonpj]:
 >  So perhaps we should accept ANY data type (GADT or whatever) with
 standalone deriving, and say "it's your fault" if the derived code doesn't
 typecheck?

 Sounds like a good idea. I've written several completely boilerplate
 instances for GADTs recently and this would have been very convenient :) I
 wouldn't find "it's your fault"-type behaviour unintuitive for
 StandaloneDeriving.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3012#comment:5>
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GHC | 1 Jul 2009 05:10
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Re: [GHC] #2979: better support for FFI C wrappers for macros in system headers

#2979: better support for FFI C wrappers for macros in system headers
---------------------------------+------------------------------------------
    Reporter:  duncan            |        Owner:                  
        Type:  feature request   |       Status:  new             
    Priority:  normal            |    Milestone:  6.12.1          
   Component:  Compiler          |      Version:  6.10.1          
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
---------------------------------+------------------------------------------
Changes (by iquiw):

 * cc: iku.iwasa <at> gmail.com (added)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2979#comment:4>
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GHC | 1 Jul 2009 06:53
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by ajd):

 What is wrong with generalizing the type of (++)? If it would not break
 too much code (on first glance, I'm not sure how it would), I think that
 that would be the best solution.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3339#comment:2>
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GHC | 1 Jul 2009 10:47
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by jochemb):

 Generalizing (++) may be confusing for newbies, but I think this is the
 best way to go.

 (+>) and (<+) are totally asymmetric, like (>>=) and (*>), whereas the
 type of (+>) is
 Monoid a => a -> a -> a

 (++) is (pretty obviously) not commutative, like (>>) and (&&), where
 there can be no confusion.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3339#comment:3>
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GHC | 1 Jul 2009 10:58
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by david48):

 In my opinion as a newbie, there are far more confusing things for newbies
 than (++) being the mappend of monoids. And anyways, monoids is far from
 being the hardest thing to understand in haskell, once you read a few well
 written blog posts.

 You can still learn to use ++ as the concatenation operator for strings,
 and discover later that there is more to it than it looks.

 I support generalizing the type of (++)

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3339#comment:4>
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GHC | 1 Jul 2009 12:37
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Re: [GHC] #454: hPutBuf doesn't respect LineBuffering

#454: hPutBuf doesn't respect LineBuffering
---------------------------------+------------------------------------------
    Reporter:  simonmar          |        Owner:                  
        Type:  bug               |       Status:  closed          
    Priority:  low               |    Milestone:  6.12.1          
   Component:  libraries/base    |      Version:  6.4             
    Severity:  normal            |   Resolution:  fixed           
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
---------------------------------+------------------------------------------
Changes (by simonmar):

  * status:  new => closed
  * resolution:  None => fixed
  * milestone:  _|_ => 6.12.1

Comment:

 The new IO library now treats `LineBuffering` like `NoBuffering` in
 `hPutBuf`.  Arguably `LineBuffering` makes little sense for a byte-
 oriented API, since the newline character might be encoded arbitrarily.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/454#comment:6>
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GHC | 1 Jul 2009 12:55
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by JulesBean):

 There is no universal convention that symmetric-looking operators should
 be commutative.

 However, it is certainly a handy visual guide.

 To address specific points:

 (&&) looks commutative to me, and it *is* commutative, in the _|_ free
 fragment of haskell. That's the fragment I most commonly reason about. You
 don't get many algebraic laws without that. Similarly (||).

 (>>) looks uncommutative - it's not about repeated symbols, it's about the
 way the > symbols obviously 'point' in one direction. And, (>>) *is*
 noncommutative, of course.

 Concrete advantages for (+>):

  * It has a symbol which visually indicates direction, and mappend is
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GHC | 1 Jul 2009 14:01
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Re: [GHC] #3339: Data.Monoid: Add (+>) as a synonym for mappend

#3339: Data.Monoid: Add (+>) as a synonym for mappend
------------------------------+---------------------------------------------
 Reporter:  bos               |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Milestone:                  
Component:  libraries/base    |        Version:  6.10.3          
 Severity:  normal            |     Resolution:                  
 Keywords:                    |       Testcase:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
------------------------------+---------------------------------------------
Comment (by duncan):

 Is there any evidence for why a flipped mappend is useful?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3339#comment:6>
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