Question

I am implementing an NFA with Ocaml and the compiler gives me an error at this line

module Nfa : NFA =
struct

type transition = int * char option * int
type nfa = int * int list * transition list

let make_nfa s fs ts = nfa (s, fs, ts);;

The error is at the last line where the compiler says Error: Unbound value nfa

I am not sure what the problem is… Thank you

Answer 1

transition and nfa are tuple type synonyms, not type constructors. Assuming you want make_nfa to be of type int -> int list -> transition list -> nfa, it would be simply

let make_nfa s fs ts = (s, fs, ts)