[m-dev.] For review: minor additions to list.m and string.m

[Ralph Becket]

> But maybe something like
> 
> 	:- func series(T, pred(T) is semidet, func(T) = T) = list(T).
> 
> 	series(Init, Test, Inc) =
> 		(   Test(Init) ->
> 			[Init | series(Inc(Init), Test, Inc)]
> 		;   []
> 		).
> 
> would be general enough to be useful often enough to bother with? 
> (This is completely untested; I hope it's close enough to correct that
> you know what I mean.)  Then if you want a geometric series you can
> always write something like series(1, >(1000), *(2)).
> 
> Kind of looks a bit like a C for loop, doesn't it?

Modulo typesetting and names, this is identical to the code I came up
with, which seems to work fine.

By the way, a while back I suggested that, just as a function without
a mode declaration is assigned a `func(in, in, ..., in) = out is det'
mode by default, a predicate without a mode declaration should have a
default mode of `pred(in, in, ..., in) is semidet'.  But I don't think
I got a response.

This crops up so often that I'd really like to see it included.  One
can always get mode inference using a compiler switch (or pragma?)

Ralph
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