Functional programming in Python

Post by recursive » Fri, May 11, 2012, 10:58 PM UTC

swannodette wrote: post #28

andreasvc wrote: post #25

Earlier quoted context omitted.

What do you mean with lack of persistent data-structures? There are immutable data-structures such as numbers, strings, tuples, and frozensets (unfortunately no frozen dicts) -- seems plenty to me. Or do you mean the technical meaning of persistent data-structures, as in one that gives access to all previous versions?

A good set of persistent data structures would give you all the generality, utility, and performance of Python data structures like lists and dicts and none of the mutability.

Post by swannodette » Fri, May 11, 2012, 11:05 PM UTC

recursive wrote: post #31

swannodette wrote: post #28

Earlier quoted context omitted.

A good set of persistent data structures would give you all the generality, utility, and performance of Python data structures like lists and dicts and none of the mutability.

I don't know about dicts, but as far as I can tell, tuples give you all the generality, utility, and performance of lists.

Post by sureshv » Fri, May 11, 2012, 11:52 PM UTC

andylei wrote: post #22

sureshv wrote: post #12

Earlier quoted context omitted.

That works but it's kind of a pain that the natural pythonic syntax: ['a'].extend(some-list) doesn't return a list.

that is not the natural pythonic syntax. for concatenating lists, "+" is standard

Post by sureshv » Sat, May 12, 2012, 12:10 AM UTC

andreasvc wrote: post #26

jlarocco wrote: post #5

Earlier quoted context omitted.

What do you mean? What would you add on top of the built-ins and stdlib data structures?

There are situations where balanced search trees are appropriate. A general purpose priority queue (with delete and decrease-key operations); there's actually code for this in the _documentation_ of the heapq module; this seems really odd to me, why not just include it? It's also a shame that heapq is built on list instead of being a first-class data-structure, it feels bolted-on. Bitwise tries would be nice as well.

Post by slig » Sat, May 12, 2012, 1:02 AM UTC

TazeTSchnitzel wrote: post #14

chimeracoder wrote: post #9

One thing that's been key for me is namedtuple (in the collections module). It's immutable like a tuple, but the values can be accessed by name just as if they were object attributes built with the class keyword. It's great for creating generic functions (think Lisp and CLOS) instead of using Python's prototypical system. And since tuples can contain any objects and functions are objects, you can bind callables like…

namedtuple is awesome, until you realise it works internally by using eval and generating the source code of a class.