Re: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
"Peter Verswyvelen" <[EMAIL PROTECTED]> writes: > Well, it's a good habit in Haskell to move the "most important" parameter to > the end of the argument list. See e.g. > http://www.haskell.org/haskellwiki/Parameter_order. I must say I like these recommendations. As for the Data.Map examples, the parameter order was changed compared to the old FiniteMap, and I was sure there was some rationale given? -k -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
Ahh ok I see what is meant by the parameter order
-Original Message-
From: Peter Verswyvelen [mailto:[EMAIL PROTECTED] On Behalf Of
Peter Verswyvelen
Sent: 03 January 2008 12:02
To: Nicholls, Mark
Cc: haskell-cafe@haskell.org
Subject: RE: [Haskell-cafe] Is there anyone out there who can translate
C# generics into Haskell?
Hi Mark,
>> "foo1 :: Int -> obj -> String"
> Yep...I think that's what I'd dothough I would have done...
> "foo1 :: obj -> Int -> String"
> Does that matter?
Well, it's a good habit in Haskell to move the "most important"
parameter to
the end of the argument list. See e.g.
http://www.haskell.org/haskellwiki/Parameter_order.
> OK but I was going to go onto
> Interface IX where A : IX {}
> and
> Interface IX where A : B {}
No, I would not know how to that in Haskell using type classes. It seems
Haskell does not allow cycles in type class definitions. But as I'm new,
this does not mean it's not possible. It's more important to know *what*
you
are trying to do, than to give a solution in a different language, since
OO
and FP are kind of orthogonal languages.
> Where I cannot see a way to do the above in Haskell at allas
> interfaces effectively operator on type classes not typeswhich
seems
> inherently more powerful
Yeah, kind of makes sense. I liked interfaces in C# a lot, but when I
started doing everything with interfaces, I found the lack of support
for
"mixins" or "default implementations" problematic. This ended up in a
lot of
copy/paste or encapsulating the implementations into a static class with
plain functions, a mess.
> But if these could be done in Haskell the see what could be made of
> stuff likewhich is obviously problematic in C# it obviously
doesn't
> workbut potentially does make 'sense'.
> Interface IX : A {}
Ah! That's one of the bigger restrictions in C# yes! C++ can do that;
ATL
uses it a lot, and I also like that approach. You can emulate "mixins"
with
that, and still stay in the single inheritance paradigm. In Haskell you
don't do that at all of course, since you avoid thinking about "objects
and
inheritance" in the first place.
OO is strange. They offer you the nice concept of inheritance, and then
the
guidelines tell you: "don't use too many levels of inheritance"...
Although
I've build huge projects using OO, it always felt a bit like unsafe
hacking.
I don't really have that feeling with Haskell, but that could also be
because I'm too new to the language ;-)
> I'm looking at Haskell because of the formality of it's type
> systembut I'm actually not convinced it is as powerful as an OO
> onei.e. OO ones operatate principally (in Haskell speak) on "type
> classes" not "types"
Maybe you are right, I don't know, my theoritical skills are not high
enough
to answer that. Haskell just "feels" better to me, although the lack of
a
friendly productive IDE and large standard framework remains a bit of a
burden.
Good luck,
Peter
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Nicholls, Mark
Sent: Wednesday, January 02, 2008 5:41 PM
To: haskell-cafe@haskell.org
Subject: [Haskell-cafe] Is there anyone out there who can translate C#
generics into Haskell?
I'm trying to translate some standard C# constucts into Haskell... some
of this seems easy
Specifically
1)
Interface IX
{
}
2)
Interface IX
{
}
3)
Interface IX
Where A : IY
{
}
4)
Interface IX : IZ
Where A : IY
{
}
I can take a punt at the first 2but then it all falls apart
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RE: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
Hi Mark,
>> "foo1 :: Int -> obj -> String"
> Yep...I think that's what I'd dothough I would have done...
> "foo1 :: obj -> Int -> String"
> Does that matter?
Well, it's a good habit in Haskell to move the "most important" parameter to
the end of the argument list. See e.g.
http://www.haskell.org/haskellwiki/Parameter_order.
> OK but I was going to go onto
> Interface IX where A : IX {}
> and
> Interface IX where A : B {}
No, I would not know how to that in Haskell using type classes. It seems
Haskell does not allow cycles in type class definitions. But as I'm new,
this does not mean it's not possible. It's more important to know *what* you
are trying to do, than to give a solution in a different language, since OO
and FP are kind of orthogonal languages.
> Where I cannot see a way to do the above in Haskell at allas
> interfaces effectively operator on type classes not typeswhich seems
> inherently more powerful
Yeah, kind of makes sense. I liked interfaces in C# a lot, but when I
started doing everything with interfaces, I found the lack of support for
"mixins" or "default implementations" problematic. This ended up in a lot of
copy/paste or encapsulating the implementations into a static class with
plain functions, a mess.
> But if these could be done in Haskell the see what could be made of
> stuff likewhich is obviously problematic in C# it obviously doesn't
> workbut potentially does make 'sense'.
> Interface IX : A {}
Ah! That's one of the bigger restrictions in C# yes! C++ can do that; ATL
uses it a lot, and I also like that approach. You can emulate "mixins" with
that, and still stay in the single inheritance paradigm. In Haskell you
don't do that at all of course, since you avoid thinking about "objects and
inheritance" in the first place.
OO is strange. They offer you the nice concept of inheritance, and then the
guidelines tell you: "don't use too many levels of inheritance"... Although
I've build huge projects using OO, it always felt a bit like unsafe hacking.
I don't really have that feeling with Haskell, but that could also be
because I'm too new to the language ;-)
> I'm looking at Haskell because of the formality of it's type
> systembut I'm actually not convinced it is as powerful as an OO
> onei.e. OO ones operatate principally (in Haskell speak) on "type
> classes" not "types"
Maybe you are right, I don't know, my theoritical skills are not high enough
to answer that. Haskell just "feels" better to me, although the lack of a
friendly productive IDE and large standard framework remains a bit of a
burden.
Good luck,
Peter
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Nicholls, Mark
Sent: Wednesday, January 02, 2008 5:41 PM
To: haskell-cafe@haskell.org
Subject: [Haskell-cafe] Is there anyone out there who can translate C#
generics into Haskell?
I'm trying to translate some standard C# constucts into Haskell... some
of this seems easy
Specifically
1)
Interface IX
{
}
2)
Interface IX
{
}
3)
Interface IX
Where A : IY
{
}
4)
Interface IX : IZ
Where A : IY
{
}
I can take a punt at the first 2but then it all falls apart
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
___
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RE: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
Can you give me a summary of why it's meaningless.both would seem to describe/construct values/objectsthey may not be equivalent, but I would expect some considerable overlap. -Original Message- From: Bulat Ziganshin [mailto:[EMAIL PROTECTED] Sent: 02 January 2008 20:29 To: Nicholls, Mark Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell? Hello Mark, Wednesday, January 2, 2008, 7:40:31 PM, you wrote: > I'm trying to translate some standard C# constucts into Haskell... some it's meaningless. read http://haskell.org/haskellwiki/OOP_vs_type_classes and especially papers mentioned in the References -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
[snip]
>-- C#: interface IX1 { String foo1(int); }
>class IX1 obj where
> foo1 :: Int -> obj -> String
Yep...I think that's what I'd dothough I would have done...
"foo1 :: obj -> Int -> String"
Does that matter?
>-- C#: interface IX2 { String foo2(A); }
>class IX2 obj a where
> foo2 :: a -> obj -> String
Ok same here
>--C#: interface IX3 where A : IY { String foo3(A); }
>class IY a where {- ... -}
>class IY a => IX3 obj a where
> foo3 :: a -> obj -> String
Yep I think again I would have guessed at that
>--C#: interface IX4 : IZ where A : IY
>class IZ a where {- ... -}
>class (IY a, IZ obj) => IX4 obj a where
> foo4 :: a -> obj -> String
H...this would have been one of my guessesbut let me have a
go...
>This assumes your "objects" are immutable, otherwise you would have to
>return (obj,String) instead of just String and then you most likely
want to
>use the state monad and "do notation" to make functional programming
look
>more like imperative programming.
This is finemy oop is largely immutable.
>You really have to drop the OO way of thinking,
>which I find the hardest :)
>Haskell's type classes are more powerful in some sense than C#
interfaces;
>for example, in C# you can't attach an interface to any class (take for
>example the Point struct), it has to be your own class, while in
Haskell,
>you can implement an instance of a type class for any datatype!
OK but I was going to go onto
Interface IX
where A : IX
{
}
And
Interface IX
where A : B
{
}
Where I cannot see a way to do the above in Haskell at allas
interfaces effectively operator on type classes not typeswhich seems
inherently more powerful
But if these could be done in Haskell the see what could be made of
stuff likewhich is obviously problematic in C# it obviously doesn't
workbut potentially does make 'sense'.
Interface IX : A
{
}
>Hope this helps a bit. As I'm new myself to Haskell, so take this with
a
>"grain of salt".
It does...I will have a go with your sample answers.
>Once you bite the bullet, I found Haskell a lot more fun than C#,
although
>C# of course comes with a gigantic .NET framework and tools...
I'm looking at Haskell because of the formality of it's type
systembut I'm actually not convinced it is as powerful as an OO
onei.e. OO ones operatate principally (in Haskell speak) on "type
classes" not "types"
>Peter
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Nicholls, Mark
Sent: Wednesday, January 02, 2008 5:41 PM
To: haskell-cafe@haskell.org
Subject: [Haskell-cafe] Is there anyone out there who can translate C#
generics into Haskell?
I'm trying to translate some standard C# constucts into Haskell... some
of this seems easy
Specifically
1)
Interface IX
{
}
2)
Interface IX
{
}
3)
Interface IX
Where A : IY
{
}
4)
Interface IX : IZ
Where A : IY
{
}
I can take a punt at the first 2but then it all falls apart
___
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Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
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RE: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
I was thinking more along type classesand then I was going to throw
some spanners in the works
From: Ryan Ingram [mailto:[EMAIL PROTECTED]
Sent: 02 January 2008 17:41
To: Nicholls, Mark
Cc: haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Is there anyone out there who can translate
C# generics into Haskell?
Of course it depends what's inside the braces, and what you want to do
with it, but I'd be inclined to do something like this:
1) data IX a = IX { constructor :: Int -> a, ... }
2) data IX a b = IX { constructor :: Int -> b, func :: a -> b, ... }
3) data IX a b = IX { iy :: IY a, ... }
4) data IX a b = IX { iz :: IZ b, iy :: IY a, ... }
Can you specify more clearly what the goal of the conversion is? If you
want "OO" style behavior the thing that is most important is existential
quantification.
-- ryan
On 1/2/08, Nicholls, Mark <[EMAIL PROTECTED]> wrote:
I'm trying to translate some standard C# constucts into Haskell... some
of this seems easy
Specifically
1)
Interface IX
{
}
2)
Interface IX
{
}
3)
Interface IX
Where A : IY
{
}
4)
Interface IX : IZ
Where A : IY
{
}
I can take a punt at the first 2but then it all falls apart
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
___
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Haskell-Cafe@haskell.org
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Re: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
Hello Mark, Wednesday, January 2, 2008, 7:40:31 PM, you wrote: > I'm trying to translate some standard C# constucts into Haskell... some it's meaningless. read http://haskell.org/haskellwiki/OOP_vs_type_classes and especially papers mentioned in the References -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is there anyone out there who can translate C# generics into Haskell?
Of course it depends what's inside the braces, and what you want to do with
it, but I'd be inclined to do something like this:
1) data IX a = IX { constructor :: Int -> a, ... }
2) data IX a b = IX { constructor :: Int -> b, func :: a -> b, ... }
3) data IX a b = IX { iy :: IY a, ... }
4) data IX a b = IX { iz :: IZ b, iy :: IY a, ... }
Can you specify more clearly what the goal of the conversion is? If you
want "OO" style behavior the thing that is most important is existential
quantification.
-- ryan
On 1/2/08, Nicholls, Mark <[EMAIL PROTECTED]> wrote:
>
> I'm trying to translate some standard C# constucts into Haskell... some
> of this seems easy
>
> Specifically
>
> 1)
>
> Interface IX
> {
> }
>
> 2)
>
> Interface IX
> {
> }
>
> 3)
>
> Interface IX
>Where A : IY
> {
> }
>
> 4)
>
> Interface IX : IZ
>Where A : IY
> {
> }
>
>
> I can take a punt at the first 2but then it all falls apart
> ___
> Haskell-Cafe mailing list
> Haskell-Cafe@haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe
>
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