public Value Visit(Expr.Application app)
{
Value fn = InterpreterVisitor.Interpret(_env, app.Fn);
if (fn.Type() != TypeName.Lambda)
{
throw new ErrorBuilder().Msg($"expected a lambda, found a {fn.Type().Display()}").Type(ErrorType.Type)
.Span(app.Fn.Span).Build();
}
Value.VLambda lam = (Value.VLambda)fn;
return(lam.Lam(new Thunk(() =>
{
Value val = InterpreterVisitor.Interpret(_env, app.Arg);
val.Span = app.Span;
return val;
})));
}
public string visit(Value.VLambda lam)
{
return("<lambda>");
}