Hi Haskellers,
Could you suggest a good place for me to learn enough real CS theory to
understand the issues and reasons behind the design and implementation of
Haskell ? My background is in pure mathematics (not logic -- differential
geometry and stuff) and most of the books I have consulted a
On Thu, 4 Nov 1999, Peter Ross wrote:
> Existential types tend to be most useful when combined with
> typeclasses. This is because you don't know what type is being
> returned, however you do know an interface which can be used with this
> type.
So this is a way to dodge the concrete-type-depend
A while ago someone mentioned the problem of several monads tending to
coalesce into one big monad, and alluded to a solution to this problem
called "monad transformers". I am struggling with this now in some code
that I am trying to sketch out. Could someone give a quick explanation of
how to
Hi everyone. I am a sometime O'Camler just learning Haskell. Type
classes are fun and I like the expressiveness you get without grafting a
whole "object system" onto your nice functional language. But sometimes
they baffle me, as in the following.
This function fails to typecheck:
-- Determina
Ah, I think I understand now. Removing '::b' from (fromInteger 1) changes
the error to:
ERROR "Matrix.hs" (line 40): Inferred type is not general enough
*** Expression: det
*** Expected type : (Ix a, Num b) => Array (a,a) b -> b
*** Inferred type : (Ix a, Num Double) => Array (a,a) Double ->
Thanks again for your help with the previous question. I have another
one. (If there is a more appropriate forum for simple questions like
this, please let me know; I don't want to waste your time.)
I am confused about the rules for constraints on polymorphic classes.
Suppose I write a class in
Here is another one for haskell-newbies, really. :)
Does anybody else wish for Ix.increment and Ix.decrement ? I have been
writing some matrix code and whenever I want to refer to "the next row
down" I have been writing (range (i0,i1))!!1, which seems inelegant.
But, it's so simple that there
I would like to add a vote for reorganization into two lists one of which
is a proper subset of the other. I stopped reading Usenet a long time ago
when the spam got too intolerable.
On the topic of the new Hugs : Is it conceivable to add the ability to
add new bindings into the top level envir
Personal taste in infix operators seems to be another good argument for a
camlp4-style preprocessor for Haskell. For instance I would like to use
'o' for composition (since anybody who uses 'o' for a variable gets what
they deserve!) but I guess that would make the lexer not so nice.
I would also
