std.algorithm: Document sort's predicate expectations #1691
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| behave as expected - otherwise, the program may fail on certain inputs (but not | ||
| others) when not compiled in release mode, due to the cursory $(D assumeSorted) | ||
| check. Specifically, $(D sort) expects $(D less(a,b) && less(b,c)) to imply | ||
| $(D less(a,c)), and, respectively, $(D !less(a,b) && !less(b,c)) to imply |
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s/, and, respectively/ (transitivity), and, conversely/
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This is a bit overkill, no? It's longer than the actual documentation... Can't we just leave it to something like /++
$(D pred) is expected to define $(WEB wikipedia.org/wiki/Total_order,
total ordering) for $(D input).
Note that the default $(D pred) of $(D "a < b") does
$(I NOT) define total ordering for floating point type
lists containing $(D NaN)s.
+/ |
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Good find regarding the "total order" term, however it doesn't seem to require or imply the negated transitivity property ( |
We can argue it's implied with transitivity, and/or "strict" total ordering? And the sentence "The default pred does not satisfy this condition" should be hint enough in itself that it is a problem. That we don't need to go into exact details of what fails where. I don't want to argue too much on documentation though. Do as you wish. Ping us when you feel it's ready. |
…-warning std.algorithm: Document sort's predicate expectations
As discussed here:
http://forum.dlang.org/post/l5u1io$18qn$1@digitalmars.com