What I don't understand is that writing a stream that unlatches a "variable" (a thing bound to a latch) executes once per time the variable is set, but it's not clear why the same code bound to a constant doesn't loop infinitely.

i.e.

i = [int\] <- 10; \i -> std.out;

executes once because i was set once.

i = [int\] <- 10; i -> std.out;

executes once because...