Please disregard the question. This is described in the User's Guide:

3.21 ocamllex, ocamlyacc and menhir

ocamlbuild knows how to run the standard lexer and parser generator  
tools ocamllex and ocamlyacc when your files have the standard .mll  
and .mly extensions.

If you want to use menhir instead of ocamlyacc, you can either launch  
ocamlbuild with the -use-menhir option or add a true: use_menhir line  
to your _tags file.

On Mar 30, 2007, at 1:17 PM, Joel Reymont wrote:

> Is there support for Menhir in ocamlbuild?
>
> Menhir uses the same 'mly' extension as ocamlyacc so I figure I  
> need to replace the default rule.

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