Re: Translating from a VERY "loose" language

["Timon Christl" <timonchristl@...>]

On 6/11/07, Steve Heller <steve@steveheller.com> wrote:
> I'm trying to do machine translation from an extremely
> "loose" language to Lua. What I mean by "loose" is
> that this language doesn't even have run-time typing.
> You can compare strings and numbers and it converts
> automatically.
>
> I need to find all the occurrences of these type
> mismatches so my Lua translation will work correctly.
> Order comparisons like '<' and '>=' will throw a
> runtime error, so I can catch them and fix the code.
> However, '==' and '~=' always produce false and true
> respectively for values that don't have the same type,
> so I won't know that there is a type mismatch.
>
> Does anyone have any suggestions as to how to catch
> these errors?

My first idea would be to try creating a metatable with an entry for
eq and attaching it to a number value. According to the manual all
number values share a single common metatable. The same applies to
strings. I don't know it this really works, but if it does it would be
everything that is needed. Note that the manual says the metatable for
non-table values can only be changed in C code.

Hope this helps

--
(defun f(p x)(If(Eq x nil)nil(If(p(Car x))(Cons(Car x)(f p(Cdr x)))(f p
(Cdr x)))))(defun q(x)(Q nil x))(defun Q(a x)(If(Eq x nil)a(Q(Cons(Car
x)(Q a(f(Lt(Car x))(Cdr x))))(f(Gt(Car x))(Cdr x)))))