HI TypeCast
Hi there!
Iam new to the list so feel free to shout at me when i do wrong! :)
Software-designer from sweden, likes fast bikes and metal, thats me, and hi
to you all!
Yeah ok to the problem,
i have this stupid code,
[c | (c,i) - l]
Where (c,i) are a tuple from a (Char,Int) and l is a [(Char,Int)]
So far everthings nice but i would like to cast the c to a Sting and add :
in front,
So if i fry with a list like [('d',3)('f',3)]
I end up with
fg but i want it to look like
:f :g
piece of cake, huh?
Give me a hit or a webpage to read more from...?
How do you TypeCast in haskell?
Cheers!
//FRedde
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Re: HI TypeCast
hello,
Fredrik Petersson wrote:
Hi there!
Iam new to the list so feel free to shout at me when i do wrong! :)
Software-designer from sweden, likes fast bikes and metal, thats me, and hi
to you all!
welcome
Yeah ok to the problem,
i have this stupid code,
[c | (c,i) - l]
Where (c,i) are a tuple from a (Char,Int) and l is a [(Char,Int)]
So far everthings nice but i would like to cast the c to a Sting and add :
in front,
So if i fry with a list like [('d',3)('f',3)]
I end up with
fg but i want it to look like
:f :g
piece of cake, huh?
Give me a hit or a webpage to read more from...?
How do you TypeCast in haskell?
no type casting in haskell. and we think of that as a feature, not a
bug :-)
having said that, you can write functions that convert values of one
type into values of another. for example:
toString :: Char - String
toString c = [c]
in Haskell the type String is the same as [Char], i.e. a string is a
list of characters.
another useful predefined function is:
concat :: [[a]] - [a]
that given a list of lists will produce a flattened list that contains
all the elements, e.g. concat [[1,2],[3,4]] = [1,2,3,4].
in particular when you take 'a' above to be Char you get:
concat :: [String] - String
which takes a list of strings and gives you back a single string
containing all the input strings.
now you can achieve what you wanted as:
concat [ : ++ toString c ++ | (c,i) - l ]
++ joins two lists into a single list. there are a lot of useful
functions in the Prelude.
hope this helped. by the way a better list to post questions when you
are stuck with a program is probably [EMAIL PROTECTED], but
people will usually reply on either list.
bye
iavor
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Re: HI TypeCast
On Wed, 6 Aug 2003, Fredrik Petersson wrote:
Hi there!
Iam new to the list so feel free to shout at me when i do wrong! :)
Software-designer from sweden, likes fast bikes and metal, thats me, and hi
to you all!
Yeah ok to the problem,
i have this stupid code,
[c | (c,i) - l]
Where (c,i) are a tuple from a (Char,Int) and l is a [(Char,Int)]
So far everthings nice but i would like to cast the c to a Sting and add :
in front,
List comprehensions are overrated =)
How about this:
concatMap ( (':':) . (:[]) . fst ) [('d',3),('f',3)]
concatMap maps a function to each element and then concatenates the list.
So the function will first use fst to extract the first element from a
tuple, then it will use (:[]) on the result to create a singleton list of
the element, then it will use (':':) which will add ':' to the front of
the list...
Now what's not clear about THAT =)
(okay so maybe list comprehensions would be clearer in this case)
How do you TypeCast in haskell?
BWUAHAHAHA!! HAHAHAA! *tears* =)
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| Tel: 073-6818655 / 031-812 817|
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| Hard Work Often Pays Off After Time|
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Re: HI TypeCast
On Wed, 6 Aug 2003 23:24:13 +0200
Fredrik Petersson [EMAIL PROTECTED] wrote:
Hi there!
Iam new to the list so feel free to shout at me when i do wrong! :)
Software-designer from sweden, likes fast bikes and metal, thats me,
and hi to you all!
Yeah ok to the problem,
i have this stupid code,
[c | (c,i) - l]
Where (c,i) are a tuple from a (Char,Int) and l is a [(Char,Int)]
So far everthings nice but i would like to cast the c to a Sting and
add : in front,
So if i fry with a list like [('d',3)('f',3)]
I end up with
fg but i want it to look like
:f :g
:d :f, ay? ;)
piece of cake, huh?
Give me a hit or a webpage to read more from...?
www.haskell.org/learning
How do you TypeCast in haskell?
You don't. Anyway's what you want isn't a typecast in any language.
concat [[':',c] | (c,i) - l]
-- actually this will give you :f:g
-- concat (intersperse [[':',c] | (c,i) - l]) will give you :f :g
-- I think intersperse is in module List (Data.List) by the way.
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