Guillaume Chatelet:
The website is more of a stopgap, the book is way better
because it
shows the paths from concepts to concepts. I should warn the
book is not
easy to read, it's hard and it hurts, but it's good hurt.
I like hard books, if they give something valuable back.
X10 ( http://x10-lang.org/ ) allows user to add constrains on
value domain definition at declaration time. Here are a few
lines took from the documentation :
* Int{self != 0} is the type of non-zero Ints.
* Int{self != 0, self != 1} is the type of Ints which are
neither zero
nor one.
* String{self != null} is the type of non-null strings.
* Matrix{self.rows == self.cols} is the type of square matrices.
I see. is that semantically different from this (beside being
shorter)?
struct NoZero {
int value;
this(int x) { value = x; }
alias value this;
invariant() { assert(value != 0); }
}
void main() {
auto a = NoZero(5);
auto b = NoZero(0);
}
Bye,
bearophile
