Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!ukma!tut.cis.ohio-state.edu!rutgers!orstcs!urania.CS.ORST.EDU!ruffwork
From: ruffwork@urania.CS.ORST.EDU (Ritchey Ruff)
Newsgroups: comp.lang.lisp
Subject: Re: The best way to save data
Keywords: save, load, lisp, Database
Message-ID: <7943@orstcs.CS.ORST.EDU>
Date: 16 Dec 88 14:57:41 GMT
References: <627@wucs1.wustl.edu>
Sender: usenet@orstcs.CS.ORST.EDU
Lines: 30

I'm in lisp and build a large data structure, then want to
save it to a file to read in later.  assume it's bound to
the atom *foo*, the problem is the reader is slow and unless
you want it even slower (by setting *PRINT-CIRCLE*) you
loose shared structure when you read it back in.  The next trick
gets around both.  This is what "foo.lisp" looks like -

	;;; foo.lisp assumes *foo* is bound to the data structure
	;;; you want to read back in later.  compile-file this
	;;; file to get a fasl file that will load quickly and
	;;; maintain shared structure that was in the original *foo*
	;;;
	(in-package 'foo)	; or whatever you want...
	;;;
	(setq *foo* '#.*foo*)

then from lisp you do 

	> (setq *foo* <some huge data structure>)
	(...)
	> (compile-file "foo")

Of course this is not human readable, and the output will
only read back into the lisp it was compiled from, but if
you are like me and need to dump 2 to 10 Meg structures to
files then read them back in this saves 2 to 5 minutes of
load time...

good luck,
--ritchey ruff