

filter :: (a > Bool) > [a] > [a]   filter, applied to a predicate and a list, returns the list of those elements that satisfy the predicate; i.e., filter p xs = [ x  x < xs, p x] 



last :: [a] > a   Return the last element in the list. The list must be nonempty. 




length :: [a] > Int   length returns the length of a finite list as an Int; it is an instance of the more general genericLength, the result type of which may be any kind of number. 








































































  All basic datatypes except for functions and IO are instances of this class. Instances of Eq can be derived for any userdefined datatype whose constituents are also instances of Eq. 



































