f (i:is) = even i : f is
f e = e
This still makes perfect sense to me... you see the let binding:
let [EMAIL PROTECTED] = e
has no additional information about the type of [] so it must be fully
polymorphic.
if the function binding we know typeOf e == typeOf (i:is) and that
i is a member
On 23 June 2004 03:53, John Meacham wrote:
Yeah, i forgot about the GC moving things around. actually, if the GC
could be coaxed to move things around, but never change the relative
order of IORefs (like a compacting collector), then the address could
still be used for Ord and Eq.
This is a
On 22 June 2004 21:44, S. Alexander Jacobson wrote:
The GHC documentation on QSem is very sparse. I
would like to give a thread exclusive access to a
resource.
My *guess* based on the documentation is that I
can create an exclusive lock using:
logSem - newQSem 1
If the maximum
On Wednesday 23 Jun 2004 10:46 am, MR K P SCHUPKE wrote:
f (i:is) = even i : f is
f e = e
This still makes perfect sense to me... you see the let binding:
let [EMAIL PROTECTED] = e
has no additional information about the type of [] so it must be fully
polymorphic.
if the function
What you are suggesting - whilst it seems reasonable requires
a fundamental change to the type system. At the moment []
signifies an empty list of type 'a' ... what you are suggesting
requires [] to have a different type from [a]... This means
a simple case statement :
case a of
On Wednesday 23 Jun 2004 12:40 pm, MR K P SCHUPKE wrote:
What you are suggesting - whilst it seems reasonable requires
a fundamental change to the type system. At the moment []
signifies an empty list of type 'a' ... what you are suggesting
requires [] to have a different type from [a]... This
Adrian Hey wrote:
I think all occurences of [] have type forall a. [a]
The case expression..
case a of
(a':as) - expr1
[] - expr2
Should be typed as if written..
case a of
(a':as) - let a=(a':as) in expr1
On Wed, 23 Jun 2004, Adrian Hey wrote:
I think all occurences of [] have type forall a. [a]
The case expression..
case a of
(a':as) - expr1
[] - expr2
Should be typed as if written..
case a of
(a':as) - let
On Wed, 23 Jun 2004, Philippa Cowderoy wrote:
Not much of use. Er, I meant to cancel that upon re-reading and following
things but ^X is next to ^C :-(
--
[EMAIL PROTECTED]
___
Haskell-Cafe mailing list
[EMAIL PROTECTED]
Well, I can live with it well enough, but I wanted to make sure I wasn't
overlooking something simple (which it appears I'm not).
#g
--
At 13:38 22/06/04 +0100, Adrian Hey wrote:
I think this was the topic of my very first post to Haskell
mailing list, many years ago..
Ah, that worked. Thank you. The MVar
documentation is also very brief.
I would also like to overwrite the contents of an
MVar atomically regardless of whether it is full
or empty. I am current using.
overWrite mvar val = tryTakeMVar mvar putMVar mvar val
But it is not atomic :-( The lib
Graham Klyne wrote:
If I have a polymorphic algebraic type (T a) with several type
constructors, only one of which actually references the type
parameter, is there any way to express type conversion for the
type-parameter-independent constructors without actually mentioning
all the
On 23 June 2004 17:13, S. Alexander Jacobson wrote:
Ah, that worked. Thank you. The MVar
documentation is also very brief.
I would also like to overwrite the contents of an
MVar atomically regardless of whether it is full
or empty. I am current using.
overWrite mvar val =
Basically, what I want is a tryReadSampleVar
function.
Or, if we stick with MVars, I don't want another
thread to operate between the tryTakeMVar and the
putMVar. In particular, I don't want another
thread to believe (mistakenly) that the mvar is
empty when it is simply being updated.
I suppose
Interesting, I think... If I understand correctly, the use of 'just' does
indeed make it rather too untyped for my taste.
It's been a while since I looked at the boilerplate work, but looking at
your code I think it depends on gmapQ of the polymorphic value to be
converted. Does your generic
On Wednesday 23 Jun 2004 2:08 pm, MR K P SCHUPKE wrote:
If I want a let binding I can write one.
The trouble with this is that a sub-optimal (I don't like to use
the word naive) implementation will actually create a new heap
construction, rather than re-use the one it knows (or should know)
it
There is a fundamental problem with assuming all []'s are equal even if
they are empty lists of different things. mainly, that they arn't!
see
; ghci
Prelude print ([]::[Int])
[]
Prelude print ([]::[Char])
Remember, in haskell, values may depend on types. Just because the type
is not
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