Reuse 'do' keyword instead of hash sign (#)

[Sam Pullara]

I'm more likely to propose we get rid of new and make it a class method than to propose another keyword that works like it :)

Sam

On Jun 20, 2011, at 10:25 AM, Dan Smith wrote:

> To clarify, I'm not necessarily suggesting that 'new' be used.  I'm saying the existence of 'new' provides a precedent for prefixing an expression with a keyword ('do', 'lambda', 'fn', etc.)
> 
> —Dan
> 
> On Jun 20, 2011, at 10:05 AM, Sam Pullara wrote:
> 
>> A long time ago I proposed that we actually use new, but that doesn't make that much sense now. Mine was more syntactic sugar for SAMs rather than lambdas:
>> 
>> new (x) { x + 1 }
>> 
>> list.filter( new (t) { t.length > 3}).map(new (t) { t.barCount}).max()
>> 
>> The nice thing about it is that it looked a lot like an anonymous inner class creation with a lot of type inference.
>> 
>> Sam
>> 
>> On Jun 20, 2011, at 9:51 AM, Dan Smith wrote:
>> 
>>> Generally speaking, you're right -- keywords are for statements.  But there is one exception: 'new'; arguably, lambda expressions and class instance creations fall into a similar class of expressions.
>>> 
>>> (As a slight digression, I think the 'if' vs. '?' parallel is useful to consider:
>>> 
>>> if (cond) statement1; else statement2;
>>> cond ? expr1 : expr2
>>> 
>>> Some points:
>>> - The statement form uses keywords; the expression form uses obscure operator characters.
>>> - Programmers seem to be comfortable understanding which to use in which contexts.
>>> - The expression form is _not_ enclosed in delimiters, and requires some "lookahead" to mentally process.
>>> 
>>> Further generalizations depend on how you feel about '?:'.  Perhaps it's a good example to model lambda expressions after.  Or perhaps it's a poorly-designed feature that scares too many beginners away, and we shouldn't use it as a model.)
>>> 
>>> —Dan
>>> 
>>> On Jun 20, 2011, at 12:11 AM, Stephen Colebourne wrote:
>>> 
>>>> No from me too.
>>>> (Keywords introduce statements in Java, not expressions.)
>>>> Stephen
>>>> 
>>>> 2011/6/18 Marcin Wiśnicki <mwisnicki at gmail.com>:
>>>>> This is a repost from 2010/8 since apparently now syntax is up for
>>>>> discussion but wasn't back then.
>>>>> Also I didn't like any proposal from "Syntax poll" thread ;(
>>>>> 
>>>>> You can call it "do" syntax ;)
>>>>> I didn't have the time to think it thoroughly or follow recent java7/8
>>>>> developments but here it goes:
>>>>> 
>>>>> Would it be possible to change the clumsy '#' operator to 'do' keyword ?
>>>>> I.e.:
>>>>> 
>>>>> do()(5)
>>>>> do(){return 5;}
>>>>> do(int x, int y) { if (x>y) return x; else return y; }
>>>>> button.onClick(do(Event e) { println("button clicked"); });
>>>>> 
>>>>> "strawman" syntax example:
>>>>> 
>>>>> list.filter( #(Foo t)(t.length() > 3) )
>>>>>   .map( #(Foo t)(t.barCount) )
>>>>>   .max();
>>>>> 
>>>>> becomes:
>>>>> 
>>>>> list.filter( do(Foo t)(t.length() > 3) )
>>>>>   .map( do(Foo t)(t.barCount) )
>>>>>   .max();
>>>>> 
>>>>> I find it more readable; using special characters feels a bit
>>>>> like perl (noisy), especially when combining multiple lambdas.
>>>>> It even makes sense if you parse it as english.
>>>>> 
>>>>> Don't know what to do with anonymous function type but it could remain as '#'.
>>>>> 
>>>>> Pros:
>>>>> - more readable
>>>>> - makes sense
>>>>> - like '#' needs only 1-lookahead to disambiguate from do-while '(' vs '{' [1]
>>>>> - did I mention it's more readable ?
>>>>> 
>>>>> Cons:
>>>>> - none (that I could think of)
>>>>> 
>>>>> [1] Automatic Resource Management from Coins wanted to use 'do' but I
>>>>> see they have switched to 'try' so no problem there.
>>>>> 
>>>>> PS. Please CC me when responding, thanks.
>>>>> 
>>>>> 
>>>> 
>>> 
>>> 
>> 
>