clarsec is an attempt to port Haskell Parsec to Clojure.
This library is inspired on http://kotka.de/projects/clojure/parser.html and uses the Meikel Brandmeyer's "monad" library (slightly adapted), as I didn't understand how the Clojure contrib monad library works.
There is an example parser which I ported straight from the Haskell Parsec code. Basically, you should be able to write the examples on http://kotka.de/projects/clojure/parser.html. The library comes with a small number of basic combinators. I hope it will be useful.
Forward references are a mess. I tried to maintain the DSL as simple as possible. Imagine that structureDef and comma are two already existing
parsers, and brackets and sepBy are two combinators. I want to be able to write it like this:
(def structure
(brackets (sepBy structureDef comma)))However, clojures def binding is strict and all the referenced vars have to be already defined, otherwise you get:
Var example/structureDef is unbound.
I'm a clojure newbie, so I don't know exactly how to avoid this. I know only of two workarounds:
;; use functions
(defn structure [] (brackets (sepBy (structureDef) (comma))))
;; use delay
(def structure (delay (brackets (sepBy structureDef comma))))I opted for the delay, as it allowed me to avoid all those spurious parens, and retain the illusion of a parser DSL, and put the delay only where needed. (or everywhere
with a defblabla macro).
Unfortunately this required a small patch to Brandmeyer's monad library.
leim jar