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Re: another nit.


Han-Wen Nienhuys <hanwen@cs.uu.nl> writes:

 > dirk@ida.ing.tu-bs.de writes:
 > > As will (set! foo bar)?  No:  There is no such thing as an unspecified
 > > object in R5RS.  R5RS says about 'unspecified':
 > > 
 > >   If the value of an expression is said to be "unspecified," then the
 > >   expression must evaluate to some object without signalling an error, but
 > >   the value depends on the implementation; this report explicitly does not
 > >   say what value should be returned.
 > > 
 > > Guile _chooses_ to return a guile-specific object, namely
 > > #<unspecified>.
 > 
 > I take it this #<unspecified> or rather SCM_UNDEFINED is here to stay,
 > is it not? In that case, there is no problem, because I can just keep
 > using my own routines instead of assq-ref. (I actually use them from
 > within C only, so I can live with implementation specificness).

You should use assq.  If it returns false then the key doesn't exist.
Otherwise the value is cdr of what assq returns.

-- 
Harvey Stein
Bloomberg LP
hjstein@bfr.co.il

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