In order to improve the error messages

[imendez]

This code:

Text SelectorLetraA(Set set)
{

Set sel = Select(set, Real(Text t) { t == "a" });
sel[1][1]

};
Set G = [["b" ? ]];
Text U = SelectorLetraA(c[1]);
Set A = EvalSet(G, Text(Set c) { SelectorLetraA(c) });

yields twice the same error because the function "SelectorLetraA" contains a
mistake, since the set "sel" can be empty, and then you can't take sel[1][1]
element.

It makes imposible to create both "A" and "U" objects, due to the same error. But
the error message that TOL returns is different:

ERROR: c no es un objeto de tipo Set.
ERROR: Argumentos erróneos para Text SelectorLetraA (Set set)
ERROR: U no se pudo crear.
ERROR: Intento de acceso al elemento 1-esimo de un conjunto de 0 elementos
ERROR: Fallo en la función "SelectorLetraA"
ERROR: Fallo en la función ""
ERROR: Fallo en EvalSet.

In the first case, you can know that "U" can't be created, but in the second case,
when trying to create "A", you only know there is a mistake in "EvalSet", so if you
have a lot of "EvalSet" in your code, you will spent much time trying to find the
error.

It's only a dummy example to show that an improvement in error and warning
messages can supply a valuable time to the analyst.

I think it's not a high-priority theme, but in the future it may be a good way to
improve TOL.

Regards

[Víctor de Buen Remiro]

Sorry by this delayed answer.

When you writes

Text U = SelectorLetraA(c[1]);

c has not be declared, and error messages are working fine in this case

If you writes

Text U = SelectorLetraA(G[1]);

then TOL will answer

ERROR: [31] Intento de acceso al elemento 1-esimo de un conjunto de 0 elementos

ERROR: [32] Fallo en la función "SelectorLetraA"

ERROR: [33] U no se pudo crear.