Is `[<var> in <distributed variable>]` equivalent to `forall`?

Question

I noticed something in a snippet of code I was given:

var D: domain(2) dmapped Block(boundingBox=Space) = Space;
var A: [D] int;
[a in A] a = a.locale.id;

Is [a in A] equivalent to forall a in A a = a.locale.id?

Answer 1

Yes, exactly. In Chapel, [a in A] expr is equivalent to forall a in A do expr.

With respect to the title of this question, note that this is independent of whether or not A is distributed. For example, you could also write [i in 1..n] rather than forall i in 1..n do.

Array types in Chapel, like [D] real can similarly be read as

"for all indices in D, allocate an element of type real."