The
print function outputs a value of any printable type to the
standard output device. Printable types are those that are instances
of class
Show;
print converts values to strings for
output using the
show operation and adds a newline.
For example, a program to print the first 20 integers and their powers
of 2 could be written as:
main = print ([(n, 2^n) | n <- [0..19]])