meg is mostly an OCaml implementation of a PEG based parser generator. It's based heavily on _why's greg
Besides actions being written in OCaml, the primary difference is that actions are expressions rather than statements.
So, with meg one would write
Expression
: a=Product '+' b=Expression { a + b }
| a=Product '-' b=Expression { a - b }
;
as opposed to, in leg/greg:
Expression
= a:Product '+' b:Expression { $$ = a + b; }
| a:Product '-' b:Expression { $$ = a - b; }
See samples/desk_calc.peg for a full translation of the desk calculator example from the peg/leg man page.
opam install .
meg samples/desk_calc.peg > samples/desk_calc.ml
ocamlc -o samples/desk_calc samples/desk_calc.ml
To install the dependencies and test dependencies without installing meg:
opam install . --deps-only --with-test
Then building and testing can be run with dune:
dune build
dune runtest
dune exec meg ...
peg/leg is copyright (c) 2007 by Ian Piumarta released under an MIT license. As is greg. As is meg.