On Tuesday 13 October 2009 02:46:29 Erik de Castro Lopo wrote:
Hi all,
I've just received the following error message:
headers.hs:6:7:
Could not find module `Control.Monad.Identity':
it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2
I'm trying to use the
Hi,
On Thursday 22 October 2009 09:47:32 Martijn van Steenbergen wrote:
Bonjour café,
data ExprF r
= Add r r
| Sub r r
| Mul r r
| Div r r
| Num Int
This is a well-known pattern that for example allows nice notation of
morphisms. But what is it called?
Hi List,
this is rather trivial, but maybe someone else finds these useful:
darcs get http://code.haskell.org/~daniels/haskell-snippets/
Especially the LANGUAGE ones have saved me quite some typing :) Additions
welcome.
Usage: If not already installed, get YASnippet:
Hi Deniz,
Cool stuff, I will probably be using this!
thanks :)
In my opinion, the naming convention is a bit inconsistent. Extension
snippets all begin with -x but imports begin with imp. I'd prefer
seeing import snippets begin with -i and use names easier to
remember, e.g. instead of
Hi,
On Friday 13 November 2009 21:08:42 Neil Mitchell wrote:
In HLint I have a bracketing module, which has served me well. Please
take any ideas you need from it -
http://community.haskell.org/~ndm/darcs/hlint/src/HSE/Bracket.hs . In
particular, given a fully bracketed expression, I can call
Hi,
- Product (a,b) and co-product (Either) of monoids
the coproduct of monoids is actually a bit tricky. It could be implemented
like this:
-- |
-- Invariant 1: There are never two adjacent Lefts or two adjacent Rights
-- Invariant 2: No elements (Left mempty) or (Right mempty) allowed
On Sunday 15 November 2009 13:05:08 Nicolas Pouillard wrote:
Excerpts from Daniel Schüssler's message of Sun Nov 15 07:51:35 +0100 2009:
Hi,
Hi,
Hi,
-- Invariant 1: There are never two adjacent Lefts or two adjacent Rights
[...]
normalize (Left a0 : Left a1 : as) = Left (mappend
Hi all,
On Wednesday 25 November 2009 22:46:42 Luke Palmer wrote:
I feel like this should be qualified. Type classes are not for name
punning ; you wouldn't use a type class for the method bark on types
Tree and Dog. But if you have a well-defined *structure* that many
types follow, then a
On Sunday 14 February 2010 17:02:36 Henk-Jan van Tuyl wrote:
The symbols that are not specified in a library can be found here:
http://www.haskell.org/haskellwiki/Keywords
Hoogle used to show links to this page, when a keyword was searched, but
not anymore.
This isn't Haskell 98 only, is
Hello Alberto,
Thank you! I don't have a problem calling for LP at hand right now, but some
time ago I was looking for such a package. Now I know where to look next time
:)
Greetings,
Daniel
On Wednesday 24 February 2010 11:07:08 Alberto Ruiz wrote:
I have uploaded to hackage an interface
On Thursday 18 February 2010 11:26:02 Ozgur Akgun wrote:
I've no idea about the GLPK system.
But, isn't it the case that you can transform any linear inequality into a
linear equality and a slack (or excess) variable?
Well yes, but the slack variables are constrained to be nonnegative, which
Hello!
The problem is that it's impossible to infer the SomeClass instance from the
type SomeRole. If you do print role, which instance should it use?
I can think of two ways around it:
-- 1. (dummy parameter)
--
data SomeRole a = Role1 | Role2 | Role3 deriving Show
Hello!
On Monday 18 May 2009 14:37:51 Kenneth Hoste wrote:
I'm mostly interested in the range 10D to 100D
is the dimension known at compile-time? Then you could consider Template
Haskell. I wrote up some code for generating the vector types and vector
subtraction/inner product below, HTH. One
Hi,
meh, I just realised that there is no sensible way to actually
introduce/eliminate the generated types. I'm attaching a revised version with
fromList/toList functions. Maybe the vector type should be polymorphic and be
an instance of Functor, Monad and Foldable? But then we really depend
Hi,
ParsecT with m=IO? Your 'do' block would become:
do
i - getInput
included - liftIO readI -- import Control.Monad.Trans for liftIO
setInput included
a - my_str
setInput i
b - my_str
return $ a ++ //\n\n ++ b
where
readI =
Hi Sjoerd,
I don't know the cause of the problem, but if I add this rule, it works:
{-# RULES
inline_map forall g x. map g x = transform (. g) x
-#}
maybe, for whatever reason, the 'map' is inlined too late for the
transform/transform rule to see it?
Greetings,
Daniel
On Monday 22 June
Hi,
On Wednesday 28 January 2009 04:30:07 John Goerzen wrote:
On Tue, Jan 27, 2009 at 09:41:30PM -0500, wren ng thornton wrote:
I once again point out that realToFrac is *wrong* for converting from
Float or Double.
realToFrac (1/0::Float) ::Double
3.402823669209385e38
with # on the end of
names, to compile with ghci. In the example below, I get a parse error
at the line defining d2f. Is this a real code snippet?
Cheers,
Dylan
On Feb 10, 2009, at 2:46 AM, Daniel Schüssler wrote:
Hi,
On Wednesday 28 January 2009 04:30:07 John Goerzen wrote:
On Tue, Jan 27, 2009
Hi,
On Sunday 01 March 2009 14:26:42 Nicu Ionita wrote:
[...]
movesFromWord8s (f:t:ws) = (f, t) : movesFromWord8s ws
moverFromWord8s _ = []
[...]
Are there possible solutions or workarounds?
for the particular problem of having to repeat the function name, you could
use case:
Although maybeRead was proposed, I cannot find it:
here's a replacement...
http://hackage.haskell.org/packages/archive/safe/0.2/doc/html/Safe.html#v%3AreadMay
Greetings,
Daniel
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
Hi,
Even worse, the buttons for moving items up and down are buggy - at
least on my browser (Firefox 3.1 beta 2 on Linux). They sometimes
reorder my other votes! Even assuming that the list box code is not
buggy (which I now doubt), not being able to use the buttons makes this
form almost
(correction of the example)
(105: ) (106: A) (107: X,B) (108: C,D) (109: E ) (110: )
moving down X will result in either
(105: A) (106: B) (107: X ) (108: C,D) (109: E ) (110: )
or equivalently
(105: ) (106: A) (107: B ) (108: X ) (109: C,D) (110: E)
On Tuesday 17 March 2009 21:03:21 Rick R wrote:
QED
Hmm? Maybe if confusingness was to be demonstrated, but not bugginess. Both
possibilities will result in the same total preordering (defined by (x
`betterThanOrEq` y) iff (numberInCombobox x = numberInCombobox y)), and
(AFAIK) only this
Hi,
On 2011-February-27 Sunday 16:20:06 Edward Amsden wrote:
Secondly,
I'd like to get to a GHC session that just has, say, Prelude in scope
so I can use dynCompileExpr with show etc, but I cannot figure out
how to bring it into scope. The closest I got was to get GHC
complaining that it
Hello,
turns out that you can define the group operation of the symmetric group on 3
elements in this abstract way (via the isomorphism to the group of bijective
functions from a three-element type to itself):
s3mult g2 g1 = fromFun (toFun g2 . toFun g1)
and convince GHC to compile it
Hello,
assuming you mean avoiding the import of Data.Map in the module *using* x, you
can use name quotations:
A.hs:
{-# LANGUAGE TemplateHaskell #-}
module A where
import Data.Map
import Language.Haskell.TH
x = varE 'empty
B.hs:
{-# LANGUAGE TemplateHaskell #-}
module B
Hello,
for reference, said instance is:
instance Monad m = Monad (Iteratee a m) where
return x = yield x (Chunks [])
m0 = f = ($ m0) $ fix $
\bind m - Iteratee $ runIteratee m = \r1 -
case r1 of
Continue k -
Hello,
you might be thinking of this type?
{-# LANGUAGE Rank2Types #-}
class Foo f where
foo :: a - f a
data Baz f a = Baz (forall f. Foo f = f a)
instance Foo (Baz f) where
foo a = Baz (foo a)
Maybe the difference between Bar and Baz ist best explained by writing it with
an
Correction: I meant
data Baz f a = Baz (Foo f = f a)
(Dropped the 'forall', which would make the inner 'f' have nothing to do with
the type parameter 'f' of 'Baz')
On 2011-June-09 Thursday 01:07:13 Daniel Schüssler wrote:
Hello,
you might be thinking of this type?
{-# LANGUAGE
-
From: Daniel Schüssler dan...@gmx.de
To: haskell-cafe@haskell.org
Cc: Guy guytsalmave...@yahoo.com
Sent: Thursday, 9 June 2011, 2:06
Subject: Re: [Haskell-cafe] Type Constraints on Data Constructors
Hello,
you might be thinking of this type?
{-# LANGUAGE Rank2Types #-}
class
On 2011-June-27 Monday 10:15:28 Yitzchak Gale wrote:
The biggest shortcoming, in my opinion, is that the documentation
assumes that the reader is very familiar with the Haskell type
system, and with viewing type signatures and instance lists as an
integral and central part of the
of how weird the type is and lets the
typechecker decide. For your GADT, this succeeds).
Cheers,
Daniel Schüssler
On 2011-August-04 Thursday 08:57:46 Tim Cowlishaw wrote:
Hi all,
I've been writing a DSL to describe securities orders, and after a lot
of help from the kind folk of this list
Hello Cafe,
say we take these standard definitions:
{-# LANGUAGE GADTs, TypeOperators, TypeFamilies, ScopedTypeVariables #-}
data a :=: b where
Refl :: a :=: a
subst :: a :=: b - f a - f b
subst Refl = id
Then this doesn't work (error message at the bottom):
inj1 :: forall f a b.
33 matches
Mail list logo
