Source : Free On-Line Dictionary of Computing

HASL
     
         {SASL} plus {conditional unification}.
     
        ["A Prological Definition of HASL, A Purely Functional
        Language with Unification Based Conditional Binding
        Expressions", H. Abramson in Logic Programming: Functions,
        Relations and Equations, D. DeGroot et al eds, P-H 1986].
     
        (1996-08-21)