Yes it seems that ++ concatenates lists not elements and that was the underlying problem.
I have subscribed to the beginners list - didn't know there was one for people like me just starting to walk :) On 3 April 2013 14:39, Brandon Allbery <allber...@gmail.com> wrote: > On Wed, Apr 3, 2013 at 5:01 AM, Angus Comber <anguscom...@gmail.com>wrote: > >> In the (x:xs) : just delimits each element. so x is the first element. >> Why can I not print by using x? >> >> Also xs is of what type? list of values? So does this mean x is an >> element and xs must be of type list? Confused... >> > > Actually, you just answered yourself. x is an element, xs is a list. (++) > combines lists, so to insert your element using (++) you need to make it a > list. [x] is a list containing your element x and nothing else. > > Another way to do it is to do the same as the pattern match, but in this > case that's kinda ugly: > > firstLetter all@(x:xs) = "The first letter of " ++ all ++ " is " ++ > (x : " otherbit ") ++ xs > > or > > firstLetter all@(x:xs) = "The first letter of " ++ all ++ " is " ++ > (x : []) ++ " otherbit " ++ xs > > (note that "is of type list" is incomplete; list of *what*? In this case, > list of Char. Haskell String is just [Char] (list of Char), which is highly > convenient but a bit slow in real programs that manipulate a lot of > String-s.) > > -- > brandon s allbery kf8nh sine nomine > associates > allber...@gmail.com > ballb...@sinenomine.net > unix, openafs, kerberos, infrastructure, xmonad > http://sinenomine.net >
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