OPAL (OPtimized Applicative Language) 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 (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

References

  • The OPAL Home Page, archived, last modified 30 September 2010.
  • OPAL Installation Guide, archived.