length package:base

Returns the size/length of a finite structure as an Int. The default implementation is optimized for structures that are similar to cons-lists, because there is no general way to do better.
Number of elements in NonEmpty list.
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.
Return the number of elements in an array, excluding the terminator
The genericLength function is an overloaded version of length. In particular, instead of returning an Int, it returns any type which is an instance of Num. It is, however, less efficient than length.
>>> genericLength [1, 2, 3] :: Int
3

>>> genericLength [1, 2, 3] :: Float
3.0
Returns the size/length of a finite structure as an Int.