On 10/15/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Before you read any more, let me just say I'm fairly new to Haskell, so > forgive > me if this is really basic stuff. > > > Hi there, I'm just wondering if there is a command for emptying a list? >
Variables in haskell do not vary. So there's not even way to add an element to a list, but there is an operator which will construct a NEW list by adding an element to the front of an EXISTING list: xs' = 'a' : xs xs' is xs but with an 'a' in front. Note that you can still access the old list xs, you never update the meaning of the variable xs, you merely create a new variable (with a new value) called xs'. So. To answer you question, no you can not change the meaning of a variable which contains a list, into all of a sudden containing the empty list. You can however use the value of the empty list, which is simply: [] > Also, is there any way to incorporate list operations (concatenation in > particular) in a do-statement on lists? Every time I try it gives a type > error. > Not quite sure what you mean. Perhaps an example of what you'd want to accomplish? /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe