Quoting Shachaf Ben-Kiki :
You can put "constraint: bytestring == version" in ~/.cabal/config.
Alternatively you can run one `cabal install --constraint "bytestring
== version"` command.
Keep in mind the following subtle difference between this constraint
and the "installed" constraint: this
Quoting Stephen Paul Weber :
Is there a way to tell cabal to refuse to upgrade a package? I'd
like to pin my `bytestring` to the version that shipped with my GHC.
cabal install --constraint "bytestring installed"
~d
___
Glasgow-haskell-users mail
It's possible that the below blog post is related.
~d
http://hackage.haskell.org/trac/ghc/blog/LetGeneralisationInGhc7
Quoting Roman Cheplyaka :
For this module
module Test where
import System.Random
data RPS = Rock | Paper | Scissors deriving (Show, Enum)
instance Random R
Quoting Jonas Almström Duregård :
Couldn't we use \\ for multi-case lambdas with layout?
Actually, \\ is a valid (infix) function name... and the base library
includes one in Data.List. That name is copied in several other
container interfaces, as well.
~d
__
Quoting wagne...@seas.upenn.edu:
Well, for what it's worth, my vote goes for a multi-argument \case. I
Just saw a proposal for \of on the reddit post about this. That's even
better, since:
1. it doesn't change the list of block heralds
2. it doesn't mention case, and therefore multi-arg \o
Quoting Mikhail Vorozhtsov :
After 21 months of occasional arguing the lambda-case proposal(s) is
in danger of being buried under its own trac ticket comments. We
need fresh blood to finally reach an agreement on the syntax. Read
the wiki page[1], take a look at the ticket[2], vote and comm
Quoting AntC :
GHC 7.2.1> :k (->) :: ?? -> ? -> *
GHC 7.4.1> :k (->) :: * -> * -> *
At first sight (->) is becoming less polyKinded. Is the eventual aim to be:
GHC 7.6+> :k (->) :: AnyKind1 -> AnyKind2 -> *
I sort of doubt it. After all, the prototypical thing to do with a
function is to
Quoting AntC :
{-# OPTIONS_GHC -XDataKinds -XPolyKinds -XKindSignatures#-}
data MyNat = Z | S Nat
class NatToIntN (n :: MyNat)
where natToIntN :: (n :: MyNat) -> Int
instance NatToIntN Z
where natToIntN _ = 0
instance (NatToIntN n) => NatToIntN (S n)
Quoting Antoine Latter :
On Thu, Feb 16, 2012 at 2:04 PM, Michael Craig wrote:
When I read the docs for System.Mem.Weak, it all seems to make sense. But
then this code doesn't run as I expect it to when I turn on
-threaded: http://hpaste.org/63832 (Expected/actual output are listed in the
past
Quoting Heka Treep :
actor mbox = do
empty <- atomically $ isEmptyTChan mbox
if empty
then actor mbox
else do
val <- atomically $ readTChan mbox
putStrLn val
actor mbox
This looks a bit silly. Why not just this?
actor mbox = forever $ atomically (readTChan mbox)
Quoting Simon Peyton-Jones :
for example. Singleton unboxed tuples are a perfectly valid data
type; it's just that we don't (now) have a name for their constructor.
Well, Haskell *does* have a mechanism for giving two different
implementations to a particular name...
class UnboxedUnit a
Quoting Bas van Dijk :
I'm playing a bit with the new ConstraintKinds feature in GHC
7.4.1-rc1. I'm trying to give the Functor class an associated
constraint so that we can make Set an instance of Functor. The
following code works but I wonder if the trick with: class Empty a;
instance Empty a,
Quoting Yitzchak Gale :
Yes. The translation of record updates given in the Report
makes perfect sense for {}. It is only forbidden by
"n >= 1", but no reason is given for that restriction.
It doesn't make sense to me. The translation explodes a value into a
case statement over its construct
Quoting Conrad Parker :
I don't think compile time is an issue for new users when building
HelloWorld.hs and getting the hang of basic algorithms and data
structures. Anyone could explicitly set -O0 if they are worried about
compile times for a larger project.
I don't agree that GHC's user int
Quoting wagne...@seas.upenn.edu:
Quoting Wolfgang Jeltsch :
this code is accepted by GHC 7.0.4:
However, this one isn?t:
{-# LANGUAGE ImpredicativeTypes #-}
polyId :: (forall a. Maybe a) -> Maybe a
polyId x = x
polyIdMap :: [forall a. Maybe a] -> [forall a. Maybe a]
polyIdMap xs = fmap po
Quoting Wolfgang Jeltsch :
this code is accepted by GHC 7.0.4:
However, this one isn?t:
{-# LANGUAGE ImpredicativeTypes #-}
polyId :: (forall a. Maybe a) -> Maybe a
polyId x = x
polyIdMap :: [forall a. Maybe a] -> [forall a. Maybe a]
polyIdMap xs = fmap polyId xs
Is there a way to make it
Quoting Jean-Marie Gaillourdet :
That sounds plausible. Do you see any workaround? Perhaps repeatedly
evaluating typeOf?
If there's a concurrency bug, surely the workaround is to protect
calls to the non-thread-safe function with a lock.
typeOfWorkaround lock v = do
() <- take
Would it be possible to have no command at all? Types are
distinguished by upper-case letters, so it should be possible to tell
whether a given expression is a value-level or a type-level expression.
I guess that's not strictly true, since the expression could be _only_
type variables -- bu
The behavior of the compilation part didn't change, GHC just started
complaining about nonsense. See
http://hackage.haskell.org/trac/ghc/ticket/5084 for more information.
~d
Quoting Antoine Latter :
Hi GHC,
Did the behavior of the INLINE prgama change in version 7.2.1? I
didn't see anythi
Hello all,
I had a bit of fun recently tracking down quoting issues with the
"system" command in Windows. For the examples below, I'll consistently
use "Windows> " as the beginning of some text sent to the Windows
command prompt cmd.exe, and use "GHC> " as the beginning of some text
sent
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