4 ms·

What is really missing is a set of decent data structures.

by pepijndevos 14y ago

jlarocco 14y ago
What do you mean? What would you add on top of the built-ins and stdlib data structures?
- swannodette 14y ago
  I believe he is talking about persistent data structures.
  - roryokane 14y ago
    Link for convenience: http://en.wikipedia.org/wiki/Persistent_data_structure http://en.wikipedia.org/wiki/Persistent_data_structure “… a persistent data structure is a data structure that always preserves the previous version of itself when it is modified. Such data structures are effectively immutable, as their operations do not (visibly) update the structure in-place, but instead always yield a new updated structure.”
- andreasvc 14y ago
  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.
  - sureshv 14y ago
    Even if heaps were a first class data-structures wouldn't the choice between trees and lists exist in the underlying implementation? Ultimately you would have to allow for both or deal with the strengths and weaknesses of that implementation.
    - andreasvc 14y ago
      As far as I know array-based heaps are most efficient with practical workloads (because it doesn't have the overhead & non-locality due to pointers for a tree structure). I don't think it's necessary to offer multiple implementations, just as there is only a single well tuned hash table in Python. What matters is that the functionality of an abstract data type is offered.
chimeracoder 14y ago
I doubt you'll see that - at least in CPython. Guido's been very clear about how he feels about implementing functional paradigms in Python, so it will probably never support functional programming in the standard implementation - just a bit in syntax/interface.
- soc88 14y ago
  I honestly don't understand that. Data structures are just code ... isn't it much more work to change syntax and interfaces instead of adding some decent implementations of data structures to the library?
  - chimeracoder 14y ago
    The syntax changes happened very much against Guido's will - he actively tried to remove lambda (and I believe map as well) for quite a while. Anyone can write whatever Python libraries they want, but I doubt anything of the sort would be added to the standard library, and certainly nothing that would require an FP-aware interpreter to optimize in a useful way.
soc88 14y ago
I agree completely. It is surprising how many Python developers are unfamiliar with it.

What is really missing is a set of decent data structures.

jlarocco 14y ago

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

swannodette 14y ago
I believe he is talking about persistent data structures.
- roryokane 14y ago
  Link for convenience: http://en.wikipedia.org/wiki/Persistent_data_structure http://en.wikipedia.org/wiki/Persistent_data_structure “… a persistent data structure is a data structure that always preserves the previous version of itself when it is modified. Such data structures are effectively immutable, as their operations do not (visibly) update the structure in-place, but instead always yield a new updated structure.”
andreasvc 14y ago
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.
- sureshv 14y ago
  Even if heaps were a first class data-structures wouldn't the choice between trees and lists exist in the underlying implementation? Ultimately you would have to allow for both or deal with the strengths and weaknesses of that implementation.
  - andreasvc 14y ago
    As far as I know array-based heaps are most efficient with practical workloads (because it doesn't have the overhead & non-locality due to pointers for a tree structure). I don't think it's necessary to offer multiple implementations, just as there is only a single well tuned hash table in Python. What matters is that the functionality of an abstract data type is offered.

chimeracoder 14y ago

I doubt you'll see that - at least in CPython. Guido's been very clear about how he feels about implementing functional paradigms in Python, so it will probably never support functional programming in the standard implementation - just a bit in syntax/interface.

soc88 14y ago
I honestly don't understand that. Data structures are just code ... isn't it much more work to change syntax and interfaces instead of adding some decent implementations of data structures to the library?
- chimeracoder 14y ago
  The syntax changes happened very much against Guido's will - he actively tried to remove lambda (and I believe map as well) for quite a while. Anyone can write whatever Python libraries they want, but I doubt anything of the sort would be added to the standard library, and certainly nothing that would require an FP-aware interpreter to optimize in a useful way.

soc88 14y ago

I agree completely. It is surprising how many Python developers are unfamiliar with it.