10 Oct
2008
10 Oct
'08
12:24 a.m.
dmehrtash:
What is the difference between empty list [] and list with one unit element [()]?
Prelude> length [] 0 Prelude> length [()] 1
Also, they differ in type. [()] is a list of unit elements, and happens to contain exactly one of them. [] is a (polymorphic) list of any kind of element, and happens not to contain any of them. Regards, John