public override bool Try(TextBuffer output, BindingEnvironment e, Continuation k,
MethodCallFrame predecessor)
{
if (!e.TryCopyGround(Value.Eval(e), out var expValue))
{
// You can't set a variable to a non-ground value
throw new ArgumentInstantiationException("set", e,
new[] { (object)GlobalVariable, Value });
}
if (LocalVariable == null)
{
return(Continue(output,
new BindingEnvironment(e,
e.Unifications,
e.State.Bind(GlobalVariable, expValue)),
k, predecessor));
}
if (e.Unify(LocalVariable, expValue, out var result))
{
return(Continue(output,
new BindingEnvironment(e, result, e.State),
k, predecessor));
}
return(false);
}
public override object Eval(BindingEnvironment e) => Operator.Implementation(Arg.Eval(e));