add duration parsing

[Swrup]

Hello,

This PR based on this draft adds duration parsing

[zapashcanon]

Hi,

Could you describe what is left to do ?

After a first quick look: could you use a more modern Menhir syntax ? Using $1 instead of named values is hard to read IMO.

[sagotch]

Hi,

Could you describe what is left to do ?

After a first quick look: could you use a more modern Menhir syntax ? Using $1 instead of named values is hard to read IMO.

Regarding how trivial the parser is, shouldn't it directly de implemented in the lexer, which would avoid the menhir dependency? Introducing this new dependency is not really a problem, but I find it to be overkill for what it does.

[Swrup]

that would be nice, but I don't know how to do it in just ocamllex