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add note about sorting with NaN

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John Clements 2015-11-24 12:18:08 -08:00 committed by Vincent St-Amour
parent 5a378ca883
commit a45330815d
1 changed files with 4 additions and 0 deletions
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pkgs/racket-doc/scribblings/reference/pairs.scrbl
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@ -534,6 +534,10 @@ either order), then the elements preserve their relative order from
@racket[sort] with a strict comparison functions (e.g., @racket[<] or
@racket[string<?]; not @racket[<=] or @racket[string<=?]).
@margin-note{Because of the peculiar fact that the IEEE-754 number system
specifies that +nan.0 is neither greater nor less than nor equal to any other
number, sorting lists containing this value may produce a surprising result.}
The @racket[#:key] argument @racket[extract-key] is used to extract a
key value for comparison from each list element. That is, the full
comparison procedure is essentially