[Haskell-cafe] Newbie list question

[Donald Bruce Stewart]

junkywunky:
> 
> type Person = (NI, Age, Balance)
> type Bank = [Person]
> 
> credit :: Bank -> [Person]
> credit [(a,b,c)] = [(a,b,c)]
> 
> This code works when I type in:
> 
> credit [(1,2,3)]
> 
> but doesn't work when I type in:
> 
> credit [(1,2,3),(4,5,6)]

You're pattern matching in 'credit' on a list of a single element.
Perhaps you mean to write:

    credit :: Bank -> [Person]
    credit x = x

or perhaps return just the first element of the list:

    credit []     = []
    credit (x:xs) = x

You might want to start with one of the tutorials on Haskell programming
listed on haskell.org. The wikibook is quite a good start.

-- Don