[Nickle]Boolean type, twixt, static vs global, built-in profiling

[Keith Packard]

Around 1 o'clock on Jul 29, Bart Massey wrote:

> If we leave things the way they are, we probably need to
> give up on the else clause of twixt(), and simply assert
> that everything should raise exceptions on failure.  Right
> now, I'm having to write
>   import File;
>   twixt((file f = open("/tmp/foo", "w")), true; close(f)) {

That makes try_acquire much less useful; I'm not sure I want it raising an 
exception when the mutex can't be grabbed.

But, the bool type has already helped me out:

	if (a & b == 0)

Without the bool type, this typechecks just fine and gives the wrong 
answer.

For your twixt example, really what you wanted was:

    import File;

    file f;

    twixt (bool func () {
        try {
            f = open ("/tmp/foo", "w");
        } catch open_error (string message, errorType error, string name) {
            return false;
        }
        return true; } ();
           close (f))
    {
        fprintf (f, "hello, world\n");
    }

This turns the exception into an appropriate boolean; of course, the lambda
could check the errorType...

> Finally, Keith, I give up: I figured out how to turn on
> Nickle-statement-level profiling, and it looks from the
> source like just printing a function ought to now show its
> per-statement profile data, but I'm afraid I'm not having
> that experience.  Suggestions?

Just a bug in the profile code when I converted to bool.  Try 
profile(false) for a good time, or update to current CVS :-)

-keith