/[guile]/guile/guile-core/NEWS
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revision 1.339 by ghouston, Sat Apr 20 21:26:05 2002 UTC revision 1.340 by mvo, Tue May 7 18:10:50 2002 UTC
# Line 20  debugging evaluator gives better error m Line 20  debugging evaluator gives better error m
20    
21  * Changes to Scheme functions and syntax  * Changes to Scheme functions and syntax
22    
23    ** There is support for Infinity and NaNs.
24    
25    Following PLT Scheme, Guile can now work with infinite numbers, and
26    'not-a-numbers'.
27    
28    There is new syntax for numbers: "+inf.0" (infinity), "-inf.0"
29    (negative infinity), "+nan.0" (not-a-number), and "-nan.0" (same as
30    "+nan.0").  These numbers are inexact and have no exact counterpart.
31    
32    Dividing by an inexact zero returns +inf.0 or -inf.0, depending on the
33    sign of the dividend.  The infinities are integers, and they answer #t
34    for both 'even?' and 'odd?'. The +nan.0 value is not an integer and is
35    not '=' to itself, but '+nan.0' is 'eqv?' to itself.
36    
37    For example
38    
39        (/ 1 0.0)
40        => +inf.0
41    
42        (/ 0 0.0)
43        => +nan.0
44    
45        (/ 0)
46        ERROR: Numerical overflow
47    
48  ** We now have uninterned symbols.  ** We now have uninterned symbols.
49    
50  The new function 'make-symbol' will return a uninterned symbol.  This  The new function 'make-symbol' will return a uninterned symbol.  This

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