Order of evaluation in application/tuple/...?

[cemerick]

The right-to-left ordering when consing should be intuitive (otherwise every additional element after the head results in a concat), but I understand the confusion re: tuples and thus arguments to functions.

This goes back to the original construction of the ZINC interpreter. The topic is a recurring one:

Why are OCaml function arguments evaluated right-to-left?

Anyone know the answer to this? I was just reminded in another thread that this order prevents the definition of the (>>) operator, which sequences 2 monadic computations. Instead, we have to use the ugly >>= fun () -> paradigm. The reason we can’t have (>>) is just that the right hand side (the latter part of the computation) would be evaluated before the left hand side (the former part of the computation). Of course, we can have (<<), but given the way monadic computation is constructed, I do…

Tuple and function execution order

I have a very basic OCaml program that reads two lines and adds them to a tuple. I expect that this tuple contains two strings in the order user inputs them (s1, s2) but strings placed in reversed order (s2, s1). Could someone explain this behavior or point me to the docs? Thanks. let () = (read_line(), read_line()) |> (fun (s1, s2) -> Printf.printf "%s\n%s\n" s1 s2);;