Syntax...

[Mark Mahieu]

It's also worth considering carefully how readable any proposed syntax will be when a lambda expression is used as a method argument, or a function type used in a method signature.  When I last looked into various options, I noted that some forms worked well in the context of a variable declaration or assignment, but were rather less easy to parse (for me, not the compiler) when they appeared as the type of a method parameter, especially when there were two or more parameters.

On another note, the link to the v0.6a Open Issues page is pointing to v0.5 at javac.info (although the correct URL isn't hard to guess :-)

Mark


On 21 Nov 2009, at 20:04, 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 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;
> 
> 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;
> 
> Cheers,
> Neal
> 
> On Sat, Nov 21, 2009 at 11:22 AM, Vladimir Kirichenko <vladimir.kirichenko at gmail.com> wrote:
> Neal Gafter wrote:
> > Are you proposing "fun" be a new keyword?
> 
> Yes. Anyway we need something for disambiguation (in current proposal
> it's # or ^). "fun" looks nice for this. (shorter than function - too
> much letters for limbda construct, and good looking next to class,
> interface and especially enum).
> 
> Other languages with pascal-like type manifestation have their let, var,
> val, set.
> 
> --
> Best Regards,
> Vladimir Kirichenko
> 
> 

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