[plt-scheme] BitField

Hi all once again,

Last week I was in need to control bits to implement RC4 private key 
algorithm in PLTScheme and I was not able to find something that would 
allow me to check bits and move them around, etc so I created a little 
module of bitfield operations. Unfortunately I think it could be better 
but had no better idea. The library is at:
http://mega.ist.utl.pt/~pocm/bitfield.ss

Any ideas, comments, corrections are welcome.

Best regards,
-- 
Paulo J. Matos : pocm(_at_)mega.ist.utl.pt
Instituto Superior Tecnico - Lisbon
Software & Computer Engineering - A.I.
  - > http://mega.ist.utl.pt/~pocm
  ---	
	Yes, God had a deadline...
		So, He wrote it all in Lisp!