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Re: trunc, round as primitive generics

From: Marius Vollmer
Subject: Re: trunc, round as primitive generics
Date: Tue, 18 May 2004 23:10:46 +0200
User-agent: Gnus/5.1002 (Gnus v5.10.2) Emacs/21.3 (gnu/linux)

Kevin Ryde <address@hidden> writes:

> In 1.6, `trunc' and `round' were primitive generics, but are now plain
> primitives.  Does that make a difference to anything?

I don't think so.  'trunc' and 'round' do not look at the type of
their argument, they use code that is already completely 'generic'.

For example, 'truncate' is

  (define (truncate x)
    (if (< x 0)
        (ceiling x)
        (floor x)))

All type dispatch is done in 'floor' or 'ceiling', which are primitive

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