Re: [Scheme-reports] Standard Feature Identifiers are too low-level

[John Cowan <cowan@x>]

Andy Wingo scripsit:

> What purpose does it serve?  If you are cond-expanding in a module, you
> already know that you have r7rs.

You might have R8RS.  More to the point, a non-conformant implementation
might have R7RS-format modules and cond-expand, but should not provide
the r7rs feature.  (There is no way to enforce this, of course; standards
can't control the behavior of implementations that don't claim conformance
to them.)

Compare the __STDC__ and __STDC_VERSION__ macros in ISO C.  If they are
defined with the correct values, the implementation conforms to ISO C
(of a particular version).  A non-conformant implementation could define
them regardless, but *it would be wrong*.

-- 
I marvel at the creature: so secret and         John Cowan
so sly as he is, to come sporting in the pool   cowan@x
before our very window.  Does he think that     http://www.ccil.org/~cowan
Men sleep without watch all night?

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