[mercury-users] Limitations of discriminated unions.

[Ralph Becket]

Bartlomiej Szymczak, Tuesday, 10 July 2007:
> Hi.
> 
> I've made a file, which contains the following:
> 
> :-module test.
> :-interface.
> :-import_module io.
> :-pred main(io::di,io::uo) is det.
> :-type t --->
> t_1;
> t_2;
> ...
> t_500000.
> :-implementation.
> main(!IO).
> 
> So main does nothing. Actually there's more than 500000 constructors.
> The file has 11MB. When I try to compile it I get the following error:
> 
> $ mmc -m test
> 
> Mercury runtime: memory zone detstack#0 overflowed
> PC at signal: 140012869 (8586d45)
> This may have been caused by a stack overflow, due to unbounded recursion.
> 
> Can't I have enumeration like that with half a million elements?

That would seem like an odd thing to do.  It doesn't surprise me that
that brings the compiler to its knees.

> Maybe someone knows how to make it work (increase compiler's stack size, 
> etc)?

I refer you to chapter 10 of the Users' Guide.  You can set the detstack
size for a Mercury program by setting the MERCURY_OPTIONS environment
variable.  For example,

MERCURY_OPTIONS="--detstack-size-kwords 8000" mmc -m test

-- Ralph
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