Dependent typing and Refinement Typing for D

[sighoya]

>Wouldn't the problem be exactly the same? You need to deduce 
>what the arguments are within the constraints, so you need to 
>analyze all paths that led to the value you submit to the 
>function to establish such constraint.

If you suggest to take values from the function body into the 
return value expression, then no, we shouldn't allow this.

What happens if we have a constant value expression in the 
function signature return value, then we need to check indeed all 
possible paths leading to this value, therefore I would only use 
it for unit tests as unit tests could be executed at compile time 
then (because of constants inputs).

Another option would be to add a runtime assertion before 
returning a value inside the function block.