Syntax...

[Vladimir Kirichenko]

Neal Gafter wrote:
> Vladimir-
> 
> We've been carefully avoiding keywords up to now, but I agree using
> keywords could result in more natural-reading programs.  The problem is
> the risk of breaking existing programs.  However, that is somewhat less

We survived "enum" I'm pretty sure "fun" is survivable too. Mostly
because of the same reasons - enum were used to implement ad-hoc enums
and "fun" most likely used with ad-hoc lambdas.

> severe now that there is a syntax for "exotic" identifiers.  In JDK7 a
> keyword can still be used as an identifier by using the exotic
> identifier escape syntax.  So the breakage is not as bad as it would
> have been earlier.  It might be possible to use context-sensitive
> keywords, too.
> 
> I would probably want to use something like 'fun' in place of '#' for
> function types, and 'lambda' or 'fun' in place of '#' for lambda
> expressions.
> 
> fun int(int) plus1 = lambda (int x) x+1;
> 
> I also prefer the result type on the right-hand-side of a function
> types, but somepeople seem to have trouble with that:
> 
> fun (int)->int plus1 = lambda (int x) x+1;

I also like currying-like syntax, but made my proposal looking back to
those somepeople :) But it's understandable (int)->int looks alien in Java.



> This latter formulation is neater-looking when there are exceptions in
> the function type.  For example, this
> 
> fun int(int) throws Exception plus1 = lambda (int x) x+1;
> 
> reads less well to me than this
> 
> fun (int) throws Exception ->int plus1 = lambda (int x) x+1;

Putting identifier in the type declaration (like regular method) was
chasing two rabbits:

1. As a preparation for short form (EBNF.3) to remove duplicate type
declaration.

       fun int increment(int x) => x + 1;

        instead  of

       fun int (int) increment = fun int (int x) => x + 1;

        notice double type declaration here.

2. Thinking about somepeople who used to see:

        int increment(int x) { return x + 1 };

       compare to:

    fun int increment(int x) => x + 1;


-- 
Best Regards,
Vladimir Kirichenko

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