[m-rev.] Re: for review: default modes for higher-order func insts

[Fergus Henderson]

On 10-Oct-2001, David Overton <dmo at cs.mu.OZ.AU> wrote:
> +++ tests/hard_coded/ho_func_default_inst.m
> @@ -17,27 +17,44 @@
>  	{ Map = map },
>  	{ F1 = Map ^ det_elem(1) },
>  	{ F2 = Map ^ det_elem(2) },
> -	io__write_string(F1(1)),
> +	io__write_int(F1(1)),
>  	io__nl,
>  	write_func(F2).
>  
> -:- type t == (func(int) = string).
> +:- type t == (func(int) = int).
...
>  :- func map = map(int, t).
>  
> -map = (map__init ^ elem(1) := hello) ^ elem(2) := world.
> +map = (((map__init
> +		^ elem(1) := foo1)
> +		^ elem(2) := foo2)
> +		^ elem(3) := foo3)
> +		^ elem(4) := foo4.
...
> +:- func foo4(int) = int.
> +:- mode foo4(in(one)) = out is det.

Surely it should be an error to insert foo4 into that map?

E.g. consider the following code:

	main -->
		{ F4 = map ^ det_elem(4) },
		io__write_int(F4(42)).

This will end up calling foo4(42), so it ought to be a mode error.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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