Possible enhancement: Concise return statements

[simendsjo]

On 15.08.2011 12:54, Timon Gehr wrote:
> Currently, when using delegates in D, there is 'return' all over the place.
> Eg:
> map!((a){return a*foo(a);})(arr);
>
> Many delegates consist of only one return statement. Writing 'return' is
> rather inconvenient and adds to the general noise.
>
> Now, I would like to propose to enhance the language in the following way:
>
> 'When the last ExpressionStatement in a function body is missing the
> ';', it is implicitly returned.'

Seems a bit error prone. I'd rather have a rule that, "If the delegate 
body only consists of a single expression, it's implicitly returned".


> The example above would become:
>
> map!((a){a*foo(a)})(arr);

"a*foo(a);"

> Multi-statement delegates would also be supported:
> {auto y=x;++x;y}();

Error, need return y;

> Probably, it would be best to disallow to use both forms of return
> statement simultaneously:
>
> {if(x) return y; z} // error

Error, use "x ? y : z;"

> I feel that this would add much to the language for both code
> readability and pleasure of writing code, especially in a functional
> style. As it is a purely additive change (currently, such code is always
> a syntax error), no existing code would be broken.
>
>
> (One indirect benefit would be that we could then require lazy arguments
> to be pure. Call by name would then be implemented by eg:
>
> int x;
> foo({x<100},{x++}); // it is evident at the call site what is going on)
>
>
>
> Any thoughts on this?
>