OCaml compilation with corebuild - ocaml

Question

I currently have a project (Go to Python compiler) with the following files
ast.ml
parser.mly
lex.mll
weeder.ml
prettyPrint.ml
main.ml
Here are the dependencies:
parser: ast
lexer: parser, Core, Lexing
weeder: ast
prettyPrint: ast
main: ast, lex, parser, weeder, prettyPrint
I try to compile doing the following which should work according to the documentation I read:
$ menhir parser.mly
> Warning: you are using the standard library and/or the %inline keyword. We
recommend switching on --infer in order to avoid obscure type error messages.
$ ocamllex lex.mll
> 209 states, 11422 transitions, table size 46942 bytes
$ ocamlbuild -no-hygiene main.native
> File "parser.mli", line 77, characters 56-59:
Error: Unbound type constructor ast
Command exited with code 2.
Compilation unsuccessful after building 6 targets (2 cached) in 00:00:00.
ast.ml contains a list of type declarations in which I have a
type ast = ...
I spent a few hours now reading doc for ocamlfind, corebuild and ocamlopt and nothing. At some point it compiled by what seemed like a mere coincidence and never worked again. I'm open to using any tool.
Here is what is in parser.mly
%{
open Ast
exception ParserError of string
let rec deOptionTypeInList tupleList =
match tupleList with
| [] -> []
| (a, Some t)::tl -> (a, t)::(deOptionTypeInList tl)
| _ -> raise (ParserError "no type given in type declaration")
%}
[ ... long list of tokens ... ]
%type <ast> prog (* that seems to be the problem *)
%type <string> packDec
%type <dec> dec
%type <dec> subDec
[...]
%start prog
[ ... rules ... ]
And here is the line, the very last, that is refereed to in the error message.
val prog: (Lexing.lexbuf -> token) -> Lexing.lexbuf -> (ast)

Answer 1

The open Ast construct will not be exported to the .mli file where the type of symbols are mentioned. Try using
%type <Ast.ast>
Edit: also, your build commands are weird. You should not call ocamllex and menhir manually, and consequently not need -no-hygiene. Remove all generated files and just do
ocamlbuild -use-menhir main.byte