Cross-language comparison: function map and similar

Sun Aug 20 02:56:47 EDT 2017

Op 2017年08月16日, Steve D'Aprano schreef <steve+python at pearwood.info>:
> Are there language implementations which evaluate the result of map()
> (or its equivalent) in some order other than the obvious left-to-right
> first-to-last sequential order? Is that order guaranteed by the
> language, or is it an implementation detail?
>> Standard library functions implementing an explicitly "parallel map"
> or "threaded map" are also relevant. (Less interested in third-party
> libraries, unless they're practically a standard for the language in
> question.)

C++17 has such a facility in its standard library.
std::transform (and many other functions operating on sequences, but
you asked for a map() equivalent) takes an optional
"execution_policy" parameter which indicates if the operation 
should be run sequentially (the default) or can be parallellized.
See: http://en.cppreference.com/w/cpp/algorithm/transform
Stephan