[plt-scheme] Immutable mappings on symbols

Carl Eastlund wrote:

 > MzScheme provides mutable hash tables keyed by symbols - actually, by
 > any data - but I can't find any functional mappings, i.e. where insert
 > and remove operations produce new mappings and preserve their inputs. I've had many occasions to want lookups based 
on symbols and it would
 > be nice to have the option of persistent data.  Is this present
 > somewhere I've overlooked, or is this a feature that could be added?


Galore provides persistent search trees.

   <http://planet.plt-scheme.org/docs/soegaard/galore.plt/1/0/doc.txt>

   <http://planet.plt-scheme.org/#galore.plt>

Comments on how to improve the library are welcome.

-- 
Jens Axel Søgaard