Opal (programming language)

OPAL (OPtimized Applicative Language) is a functional programming language first developed at the Technical University of 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 (declaration)

SIGNATURE GCD FUN GCD: nat ** nat -> nat


 * Implementation file (definition)

IMPLEMENTATION GCD IMPORT Nat COMPLETELY DEF GCD(a,b) == IF a % b = 0 THEN b                       ELSE IF a-b < b THEN GCD(b,a-b) ELSE GCD(a-b,b) FI FI