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Every time I see this pattern, a part of me dies inside. collection = [] for i in data: collection.append(fn(i)) Why not just [fn(i) for

Every time I see this pattern, a part of me dies inside. collection = [] for i in data: collection.append(fn(i)) Why not just [fn(i) for i in data] ?

wingerlang 11y ago
First example is way, WAY, more readable. Honestly, if I didn't read the first one I would probably not have figured out what the other one does without research.
- merb 11y ago
  You are kidding. The Map one exactly describe what it does. it 'maps' the data. Which means it describes it in the way function fn is telling it. Which is really easy to read if you understand english...
  - wingerlang 11y ago
    > Which is really easy to read if you understand english Maybe I missed something, but how does this > [fn(i) for i in data] read easier if you know english? You need to know the syntax of "[...]" to know what it does. The top/first example, however, actually reads like english.
    - tschuy 11y ago
      List comprehension are a very common thing in Python. If you knew Python you'd know exactly what that means. But zokier is right, a map is probably a better choice here.
    - s_kilk 11y ago
      >> You need to know the syntax of "[...]" to know what it does. Anyone with even a basic understanding of python (the language of the examples we've been discussing here) should know this syntax. If they didn't I'd be worried.
    - merb 11y ago
      I never talked about fn(i) for i in data. That's pythonic as somebody explain but the map one is the most readable and appears in more and more languages, even Java.
zokier 11y ago
If we are nitpicking then why not map(fn, data) ?
- bpicolo 11y ago
  List comprehensions are more direct, support more than just a function call, and in py3 map returns an iterable instead of a list (granted, easily solvable by list(map()) but it's an extra concern) List comprehensions are the very recommended strategy for constructing python lists, not to mention they're simply a fantastic language feature. Very direct, readable, and hard to get wrong. Python loses out a lot on it's functional sorts of functions (filter, map) because you can't use method chaining on a list for them, imo
m1el 11y ago
You are right, list comprehension are cool and I often use them. However, in this particular case, IMO, it would make things worse because I would have to write a multi-line list comprehension. Multi-line list comprehensions have bad readability. The object literal is too big to be included in list comprehension. I could move commit->object conversion to a function, but then I would have used map. And it would have created one more indirection. The current state is my deliberate choice.

Every time I see this pattern, a part of me dies inside. collection = [] for i in data: collection.append(fn(i)) Why not just [fn(i) for i in data] ?

wingerlang 11y ago

First example is way, WAY, more readable. Honestly, if I didn't read the first one I would probably not have figured out what the other one does without research.

merb 11y ago
You are kidding. The Map one exactly describe what it does. it 'maps' the data. Which means it describes it in the way function fn is telling it. Which is really easy to read if you understand english...
- wingerlang 11y ago
  > Which is really easy to read if you understand english Maybe I missed something, but how does this > [fn(i) for i in data] read easier if you know english? You need to know the syntax of "[...]" to know what it does. The top/first example, however, actually reads like english.
  - tschuy 11y ago
    List comprehension are a very common thing in Python. If you knew Python you'd know exactly what that means. But zokier is right, a map is probably a better choice here.
  - s_kilk 11y ago
    >> You need to know the syntax of "[...]" to know what it does. Anyone with even a basic understanding of python (the language of the examples we've been discussing here) should know this syntax. If they didn't I'd be worried.
  - merb 11y ago
    I never talked about fn(i) for i in data. That's pythonic as somebody explain but the map one is the most readable and appears in more and more languages, even Java.

zokier 11y ago

If we are nitpicking then why not map(fn, data) ?

bpicolo 11y ago
List comprehensions are more direct, support more than just a function call, and in py3 map returns an iterable instead of a list (granted, easily solvable by list(map()) but it's an extra concern) List comprehensions are the very recommended strategy for constructing python lists, not to mention they're simply a fantastic language feature. Very direct, readable, and hard to get wrong. Python loses out a lot on it's functional sorts of functions (filter, map) because you can't use method chaining on a list for them, imo

m1el 11y ago

You are right, list comprehension are cool and I often use them. However, in this particular case, IMO, it would make things worse because I would have to write a multi-line list comprehension. Multi-line list comprehensions have bad readability. The object literal is too big to be included in list comprehension. I could move commit->object conversion to a function, but then I would have used map. And it would have created one more indirection. The current state is my deliberate choice.