ocaml - unbound value error in recursive list matching function

Question

I copied a recursive list matching function from a slide of an introductory ocaml course.

let rec fac n = match n with
     0 -> 1
     | _ -> n * fac(n-1);;

fac 3;;

I get: "Error: Unbound value fac"

Why is this?

ok, if I run it in the interactive mode, it works. But if I run it from the editor it doesn't — user3435407, Sep 27 '17 at 11:27
I'll bet you forgot to put `rec` keyword when you ran it. It's one of the common mistakes for this error message. — Pandemonium, Sep 28 '17 at 00:03
You have to explain exactly what you did in Emacs. I roughly guess you might execute `tuareg-eval-phrase` only on `fac 3`, not evaluating the function definition prior to it. — camlspotter, Sep 28 '17 at 00:48

score 0 · Answer 1 · answered Apr 17 '18 at 10:14

Using M-X tuareg-eval-buffer in emacs gives:

        OCaml version 4.02.3

# let rec fac n = match n with
     0 -> 1
     | _ -> n * fac(n-1);;

fac 3;;
    val fac : int -> int = <fun>
#   - : int = 6
#

You probably run M-X tuarge-eval-region with only the fac 3 selected so the function was never defined.

ocaml - unbound value error in recursive list matching function

1 Answers1