Source code in the icon programming language

procedure main()
   testproc("x:=",1,"y:=",2,"z:=",3)
   testproc("x:=",3,"y:=",1,"z:=",2)
   testproc("z:=",4,"x:=",2,"y:=",3)
   testproc("i:=",1,"y:=",2,"z:=",3)
end

procedure testproc(A[])   #: demo to test named parameters
   write("Calling testproc")

   while a := get(A) do               # implement named parameters here
      (( a ? (v := =!["x","y","z"], =":=")  |   #  valid parameter name?
         stop("No parameter ",a)) &             #  . . no
            ((variable(a[1:-2]) := get(A))  |   #  assign
               runerr(205,a)))                  #  . . problem

   write("   x:=",x)
   write("   y:=",y)
   write("   z:=",z)
end