On Tue, 2009-01-27 at 10:05 -0800, Corey O'Connor wrote:
> On Tue, Jan 27, 2009 at 4:51 AM, wrote:
> > Doug McIlroy wrote:
> >> A fragment of an attempt to make pairs serve as complex numbers,
> >> using ghc/hugs extensions:
> >>
> >> instance Num a => Num (a,a) where
> >>
Corey O'Connor wrote:
> On Tue, Jan 27, 2009 at 4:51 AM, wrote:
>> Doug McIlroy wrote:
>>> A fragment of an attempt to make pairs serve as complex numbers,
>>> using ghc/hugs extensions:
>>>
>>> instance Num a => Num (a,a) where
>>> (x,y) * (u,v) = (x*u-y*v, x*v+y*u)
>>
On Tue, Jan 27, 2009 at 4:51 AM, wrote:
> Doug McIlroy wrote:
>> A fragment of an attempt to make pairs serve as complex numbers,
>> using ghc/hugs extensions:
>>
>> instance Num a => Num (a,a) where
>> (x,y) * (u,v) = (x*u-y*v, x*v+y*u)
> The recent versions of GHC have a
In ghc 6.10.1 the ~ constraint is working:
{-# LANGUAGE TypeFamilies #-}
{-# OPTIONS -fglasgow-exts #-}
{-# OPTIONS -fallow-undecidable-instances #-}
module D where
instance (Num a, Num b, a ~ b) => Num (a,b) where
(x,y) * (u,v) = (x*u-y*v, x*v+y*u)
test1 = (1,1) * (2,2)
test2 = (1,1.0)
Doug McIlroy wrote:
> A fragment of an attempt to make pairs serve as complex numbers,
> using ghc/hugs extensions:
>
> instance Num a => Num (a,a) where
> (x,y) * (u,v) = (x*u-y*v, x*v+y*u)
>
> Unfortunately, type inference isn't strong enough to cope with
>
> (1,1
Lennart Augustsson wrote:
>> I had hoped that the code below (GHC 6.10+) would work, but it just
>> sends GHC into a loop when you actually try to typecheck (1,1). I
>> don't know if that's a bug in GHC or a misunderstanding on my part of
>> how the typechecking should work.
> A loop without turn
A loop without turning on a flag to allow it must be a bug.
-- Lennart
On Mon, Jan 19, 2009 at 2:04 PM, Sittampalam, Ganesh
wrote:
> Doug McIlroy wrote:
>> A fragment of an attempt to make pairs serve as complex numbers,
>> using ghc/hugs extensions:
>>
>> instance Num a => Num (a,a) w
Doug McIlroy wrote:
> A fragment of an attempt to make pairs serve as complex numbers,
> using ghc/hugs extensions:
>
> instance Num a => Num (a,a) where
> (x,y) * (u,v) = (x*u-y*v, x*v+y*u)
>
> Unfortunately, type inference isn't strong enough to cope with
>
> (
Doug McIlroy wrote:
> instance Num a => Num (a,a) where
> (x,y) * (u,v) = (x*u-y*v, x*v+y*u)
>
> Unfortunately, type inference isn't strong enough to cope with
>
> (1,1)*(1,1)
I'm guessing it is because
(fromInteger 1, fromInteger 1) :: (Num a, Num b) => (a
A fragment of an attempt to make pairs serve as complex numbers,
using ghc/hugs extensions:
instance Num a => Num (a,a) where
(x,y) * (u,v) = (x*u-y*v, x*v+y*u)
Unfortunately, type inference isn't strong enough to cope with
(1,1)*(1,1)
Why shouldn't it be strengt
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