On Wed, Mar 16, 2016 at 10:57 AM, Steven D'Aprano <st...@pearwood.info> wrote:
> There's a powerful technique used in shell-scripting languages like bash: > pipes. The output of one function is piped in to become the input to the > next function. > > According to Martin Fowler, this was also used extensively in Smalltalk: > > http://martinfowler.com/articles/collection-pipeline/ > > and can also be done in Ruby, using method chaining. > > Here is a way to do functional-programming-like pipelines to collect and > transform values from an iterable: > > https://code.activestate.com/recipes/580625-collection-pipeline-in-python/ > > For instance, we can take a string, extract all the digits, convert them to > ints, and finally multiply the digits to give a final result: > > py> from operator import mul > py> "abcd12345xyz" | Filter(str.isdigit) | Map(int) | Reduce(mul) > 120 > > > (For the definitions of Filter, Map and Reduce, see the code at the > ActiveState recipe, linked above). In my opinion, this is much nicer > looking that the standard Python `filter`, `map` and `reduce`: > > py> reduce(mul, map(int, filter(str.isdigit, "abcd12345xyz"))) > 120 > > as this requires the operations to be written in the opposite order to the > order that they are applied. > > > This is interesting, but the part I'm missing is the use of the Pipe symbol '|' in python. Can you elaborate > > -- > Steven > > -- > https://mail.python.org/mailman/listinfo/python-list > -- Joel Goldstick http://joelgoldstick.com/ <http://joelgoldstick.com/stats/birthdays> http://cc-baseballstats.info/ -- https://mail.python.org/mailman/listinfo/python-list
