The Free On-line Dictionary of Computing (30 December 2018):

Goffin

    A definitional constraint language for
   declarative parallel programming.  Goffin systematically
   integrates equational constraints and functions within a
   uniform framework of concurrent programming.

   Goffin is an embedding of a functional language kernel
   (Haskell) into a layer of constraint logic, which allows
   logical variables inside functional expressions.  In order
   to preserve referential transparency, functional reduction
   suspends until logical variables become bound.

   Logical variables are bound by equational constraints, which
   impose relations over expressions.  Hence, constraints are the
   means to structure the concurrent reduction of functional
   expressions.

   (1995-02-21)