Re: Namestring&pathstring returning shared structure

[Pavel.pa@Xerox.COM]

	Date: Mon, 23 Jun 86 10:03 EDT
	From: David C. Plummer <DCP@QUABBIN.SCRC.Symbolics.COM>
	
	It must be a bitch to write an editor in CLU, or do you just implement
	lines as arrays of characters instead of as strings, thereby losing the
	textual benefit of debugging and having to write separate output
	routines to display these "strings"?

The Cedar system at PARC provides an immutable string type called ROPE's
(thick strings) and the editor in fact uses them.  Once you know that
the strings are immutable, you can play all sorts of fun games with
their representation, including sharing structure all over the place and
getting (nearly) constant-time concatenation and substring operations
with very slightly degraded fetch performance.  Immutable strings are an
extremely big win and I hope to have us (Xerox) implement them for our
Lisp in the relatively near future.

	Pavel