Opal (programming language)
OPAL is a functional programming language first developed at Technische Universität Berlin.
There is a later framework for static code analysis also called Opal.
Example program
This is an example OPAL program, which calculates the GCD recursively.; Signature file
SIGNATURE GCD
FUN GCD: nat ** nat -> nat
; Implementation file
IMPLEMENTATION GCD
IMPORT Nat COMPLETELY
DEF GCD IF a % b = 0 THEN b
ELSE IF a-b < b THEN GCD
ELSE GCD
FI
'''FI'''