[plt-scheme] 4.0 question

Matthew Flatt wrote:

> Structures are immutable by default:

Okay, good. It doesn't say that in the documentation:

http://pre.plt-scheme.org/docs/html/guide/define-struct.html

but I know that is lagging behind.

> Since mutations to variable are lexically apparent (in a `module'
> world), they do not create anywhere near as much trouble.

That makes sense, especially in light of R6RS. --PR