[PEP] matching and mismatching

[Luke Kenneth Casson Leighton]

this is an initial proposal idea which i would like to bounce around
with people, to find out if it's a good idea or even in fact if
something
like it has already been added or considered.

the idea: a function/operator similar to map and reduce _or_ a keyword
similar to "in", such that:

for x in ([1,3,2,5,9] matching lambda x:x > 2):
	print x
will output:
3
5
9

or the equivalent to like map/reduce:

print matching([1,2,3], lambda x:x > 2)
will output:
[3]

now, the justification for this, instead of having this:

for x in [1,3,2,5,9]:
	if x > 2:
		print x

is for parallelisation reasons.

the for-loop-plus-if-statement cannot be expected to be
parallelised [in a massively parallel architecture] because
the code-flow is _expected_ to be sequential.

a matching (and its corresponding mismatching) operator/function
_could_, like map, be parallelised, and optimised on parallel
hardware / co-processor support.

what do people think?

luke.

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