automated conversions between OCaml-values and S-expressions

 Sexplib library contains functionality for parsing and pretty-printing
 S-expressions.
 .
 Sexplib also contains a preprocessing module for Camlp4, which can be
 used to automatically generate code from type definitions for
 efficiently converting OCaml-values to S-expressions and vice versa.
 In combination with the parsing and pretty-printing functionality this
 frees users from having to write their own I/O-routines for the
 datastructures they define. Possible errors during automatic
 conversions from S-expressions to OCaml-values are reported in a very
 human-readable way.
 .
 Another module contained in Sexplib you to extract and replace
 sub-expressions in S-expressions.