A list comprehension is a special syntax in some programming languages to describe lists. It is similar to the way mathematicians describe sets, with a set comprehension, hence the name.

Some attributes of a list comprehension are:

 They should be distinct from (nested) for loops and the use of map and filter functions within the syntax of the language.
 They should return either a list or an iterator (something that returns successive members of a collection, in order).
 The syntax has parts corresponding to that of set-builder notation. 


Task

Write a list comprehension that builds the list of all Pythagorean triples with elements between   1   and   n.

If the language has multiple ways for expressing such a construct (for example, direct list comprehensions and generators), write one example for each.




pythag = fn (N) {
    [(A, B, C) for A in lists.seq(1, N) \
         for B in lists.seq(A, N) \
         for C in lists.seq(B, N) \
         if A + B + C <= N and A * A + B * B == C * C]
}
 
@public 
run = fn () {
    io.format("~p~n", [pythag(20)])
}
 