Andrej Bauer wrote:
> let fib, fib_mem =
>   let fib' self = function
>     | 0 -> 0
>     | 1 -> 1
>     | n -> self (n - 1) + self (n - 2)
>   in
>     make_rec fib', make_mem fib

I apologize, the last line should read

   make_rec fib', make_mem fib'

An apostrophe is missing.

Andrej