[m-rev.] for review: merge foreign_type pragma on to the main branch

[Fergus Henderson]

On 23-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> +++ foreign.m	23 Oct 2001 14:31:56 -0000
> @@ -496,9 +496,82 @@
>  		FM = qualified(Module, Name ++ Ending)
>  	).
>  
> +%-----------------------------------------------------------------------------%
>  
> +:- import_module hlds_data.

That should go at the start of the implementation section.

> +:- type export
> +	--->	foreign(sym_name)
> +	;	mercury((type)).

That type should be documented, and you should use more meaningful names.

> +:- func to_type_string(foreign_language, export_type) = string.

The intended semantics of that function should be explained.

> +to_type_string(c, foreign(Foreign)) = 
> +	error("to_type_string: c NYI").
> +to_type_string(csharp, foreign(Foreign)) = _ :-
> +	Result = sym_name_to_string(ForeignType, ".").
> +to_type_string(managed_cplusplus, foreign(Foreign)) = _ :-
> +	Result = sym_name_to_string(ForeignType, ":") ++ " *".
> +to_type_string(il, foreign(Foreign)) = _ :-
> +	error("to_type_string: il NYI").

Use sorry/2 rather than error/1.

Shouldn't all these NYI bits be implemented?

> +to_type_string(c, mercury(Type)) = Result :-
> +	( Type = term__functor(term__atom("int"), [], _) ->
> +		Result = "MR_Integer"
> +	; Type = term__functor(term__atom("float"), [], _) ->
> +		Result = "MR_Float"
> +	; Type = term__functor(term__atom("string"), [], _) ->
> +		Result = "MR_String"
> +	; Type = term__functor(term__atom("character"), [], _) ->
> +		Result = "MR_Char"
> +	;
> +		Result = "MR_Word"
> +	).

Won't that do the wrong thing for type variables with --high-level-code?
Shouldn't the type for those be "MR_Box"?

Ah, thinking about it a bit more, I see that this code is correct.
But a comment or two here, explaining why, might help.

Also, isn't this code the same as export__type_to_type_string?
Why does this code need to be duplicated?

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  | "... it seems to me that 15 years of
The University of Melbourne         | email is plenty for one lifetime."
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- Prof. Donald E. Knuth
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