[plt-scheme] immutable? and numbers

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Wed Sep 17 09:15:44 EDT 2008

At Tue, 16 Sep 2008 17:37:14 -0300, "Gustavo Massaccesi" wrote:
> I tried this:
> 
> --------
> Welcome to DrScheme, version 372 [3m].
> Language: Textual (MzScheme, includes R5RS) custom.
> > (immutable? 5)
> false
> >
> --------
> 
> I was surprised because it returns #f and not #t.
> 
> It is the correct behaviour, according to the manual. But, since it is
> impossible to mutate 5, it is not the result I expected.

Agreed. `immutable?' really should have been called something like
`immutable-variant-of-datatype-that-could-be-mutable?'.


Matthew



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