Seem to have to same motivation as list comprehensions. Syntax in Python 2.3 for "iterator comprehensions," which would Operating on "lazy sequences" (iterators) rather than onĬompleted sequences (lists, tuples). Module is composed of function of the very same sort, merely On the one hand, many Pythonĭevelopers disparage the traditional FP functions map(),įilter(), and reduce()-usually recommending using listĬomprehensions in their place. There is something schizophrenic in Python's attitudes towardsįunctional programming (FP). Iter(seq)-this will not save any memory, but it can be Way, a true sequence can be turned into an iterator by calling Iterator.next() raises a StopIteration exception. The loop is terminated when the behind-the-scenes call to Method that can be invoked explicitly, but 99% of the time, what Most of the time, an iterator is utilized within a for loop, Of other sequences can best be treated lazily too-they mightĭepend on data arriving incrementally over a channel, or upon a There is no need to store the whole file in memory. Types of files, processing can be a line-by-line matter, and General need for it to claim a lot of memory. Program will probably take a while to execute, but there is no If you want to do something a billion times, your The x*() premonitions provide clear examples of these The motivation behind iterators is twofold: (1) Working with dataĪs sequences is very frequently the most straightforwardĪpproach (2) A sequence that is processed in linear order oftenĭoes not need to actually exist all at once. Presence of yield turns a function into a generator, which in Much more straightforward by introducing the yield keyword (the Internal implementation, and made programming custom iterators Python 2.2 generalized the notion in much of its Present in the older function xrange(), and the file method Well, that is not quite true: hints of the idea were already The idea of iterators was introduced into Python with versionĢ.2. Module, and gives reader a sense of the new expressive power Modules is essentially a set of combinatorial higher-orderįunctions, but ones that work with lazy iterators rather Think more capabilities will be introduced to this module,īut already it is a very interesting thing. Introduced to work flexibly with iterators. Need for _future_), and the new module itertools is With Python 2.3, generators become standard (no Python 2.2 introduced simple generators to Python language,Īnd reconceived standard loops in terms of underlying CHARMING PYTHON #B13: The module - Functional programming in Python becomes lazy - Charming Python #b13: The itertools Module Functional programming in Python becomes lazy
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |