function returns list in reverse order in OCaml

Question

I want to read some numbers from a file, take them to a list and finally display them on the screen. numbers.txt currently has 2 3 5 7 11 however as output i\'a

Answer 1

The order of evaluation of arguments is unspecified in OCaml. So when you do f x :: g y, it is unspecified whether f or g gets called first. In your case the recursive call is invoked before the call to bscanf, which is why you get the results in the wrong order.

The general way to fix evaluation-order issues is to put the arguments to a function into local variables when the order of their side effects matters. So instead of f x :: g y, you'd do let fx = f x in fx :: g y if you want the effects of f x to happen before g is called.

However in your case you can just make use of bscanf's continuation argument like this:

bscanf sb " %d" (fun a -> a :: int_list_from_sb sb (n - 1))