String lambdas

[Bauss via Digitalmars-d]

On Tuesday, 26 April 2016 at 17:58:22 UTC, Andrei Alexandrescu 
wrote:
> https://github.com/dlang/phobos/pull/3882
>
> I just closed with some regret a nice piece of engineering. 
> Please comment if you think string lambdas have a lot of 
> unexploited potential.
>
> One thing we really need in order to 100% replace string 
> lambdas with lambdas is function equivalence. Right now we're 
> in the odd situation that SomeTemplate!((a, b) => a < b) has 
> distinct types, one per instantiation.
>
>
> Andrei

An alternative to string lambads could be something like a 
shortened version of lambdas like consider

"a > b" could be something like {%0 > %1} and then the body of 
the expression is evaluated to see whether it's a valid D 
expression where %1 and %2 would equal first and second arguments 
in the expression and when used you could simply use do something 
like

Compare(T,expression)(T x, T y) {
     return expression(x,y); // the compiler has to figure out 
that this should be evaluated as return x < y with the example 
above.

This will ensure that the expression is a valid D expression and 
cannot really hacked to do other stuff what it's meant to.

Of course this is just an idea on top of my head on how string 
lambdas could be resolved.