On 10/15/05, poogle@netspace.net.au
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