S-Expression parsing/printing made fun and easy
sexp provides an S-expression data-type, and printers and parsers
that work on all data-types that have Generic instances (so,
everything you're ever likely to define yourself).
In order to encode/decode a custom data-type with sexp, 1) add a
Generic instance for it, and 2) add an empty Sexpable instance
for it. The default implementation of Sexpable's toSexp and
fromSexp uses the Generic representation of the data-type to
encode and decode it.
In order to print a Sexp, use printHum (for human-friendly
output), or printMach (for human-unfriendly output). In order to
parse a Sexp, use parse and friends.
See the documentation on Hackage for details.
% ghci
GHCi, version 7.6.2: http://www.haskell.org/ghc/ :? for help
λ > :set -XDeriveGeneric
λ > import Language.Sexp
λ > import GHC.Generics
λ > data MyType = Foo { unFoo :: Int, getBar :: Double } deriving ( Show, Generic )
λ > instance Sexpable MyType
λ > toSexp (Foo 23 42.0)
List [Atom "Foo",List [List [Atom "unFoo",Atom "23"],List [Atom "getBar",Atom "42.0"]]]
λ > printMach (toSexp (Foo 23 42.0))
"(Foo ((unFoo 23) (getBar \"42.0\")))"
λ > parseExn (printMach (toSexp (Foo 23 42.0)))
[List [Atom "Foo",List [List [Atom "unFoo",Atom "23"],List [Atom "getBar",Atom "42.0"]]]]
λ > fromSexp (head (parseExn (printMach (toSexp (Foo 23 42.0))))) :: Maybe MyType
Just (Foo {unFoo = 23, getBar = 42.0})
This package is on Hackage. To install it, run:
cabal update
cabal install sexp