5 ms·

For me the decisive advantage Ruby has over Python is way better map/reduce/select semantics. Python's list comprehensions are just ungainly to me, and I've nev

by akanet 8y ago

For me the decisive advantage Ruby has over Python is way better map/reduce/select semantics. Python's list comprehensions are just ungainly to me, and I've never understood the reverence for them.

maksimum 8y ago
I think one reason people like comprehensions in python is because they provide an intuitive syntax for both map and select/filter. As I understand it, reduce still provides functionality that you can't get from comprehensions alone. I feel like comprehensions are expressive and readable unless you try to do multiple maps in the same comprehension. I looked up the select/filter syntax in ruby. I guess the main difference is that the name of the element you're iterating over is left implicit compared to comprehensions, but equivalent to filter. details.select{ |item| item[:qty] != "" } [item for item in details if item.qty != ''] filter(lambda item: item.qty != '', items) I'm curious if the implicitness is cumbersome when you need to do a selection that combines multiple lists. How would you express the third line of the following in ruby? A = range(65,69) B = ['A', 'B', 'C', 'D'] [a for a, b in zip(A, B) if b=='C']
- onli 8y ago
  My approach would probably be to create the zipped list in the beginning, split it for the comparison and then select the wanted element: A = (65..69).to_a B = ['A', 'B', 'C', 'D'] A.zip(B).select{|x, y| y == 'C' }.map{|x, y| x }
  - maksimum 8y ago
    Thanks! That looks equivalent to python without comprehensions. As far as I can tell the difference in the expressiveness of `map/filter/reduce` is mainly about whether you like or don't like comprehensions. Do you have any examples where you believe ruby has cleaner syntax?
    - dragonwriter 8y ago
      > As far as I can tell the difference in the expressiveness of `map/filter/reduce` is mainly about whether you like or don't like comprehensions. Comprehensions don't replace reduce, they are equivalent to a combination of map, filter, and flat_map. The difference is not just about comprehensions, since map/filter/reduce, and friends, in Python are functions, where in Ruby they are methods; so in Python when you can't do it all with comprehensions (reduce, zip, etc.), it's either imperative loops or functional notation (inside-out), while Ruby uses method call notation, which results in operations reading in the order of application.
      - maksimum 8y ago
        Great clarification. You're right, reduce was a typo. I definitely like how method call notations can be read left-to-right rather than inside out. Now I'm curious why python developers decided not to add these 'transformation methods' to all Iterables.

by akanet 8y ago

For me the decisive advantage Ruby has over Python is way better map/reduce/select semantics. Python's list comprehensions are just ungainly to me, and I've never understood the reverence for them.

maksimum 8y ago

I think one reason people like comprehensions in python is because they provide an intuitive syntax for both map and select/filter. As I understand it, reduce still provides functionality that you can't get from comprehensions alone. I feel like comprehensions are expressive and readable unless you try to do multiple maps in the same comprehension. I looked up the select/filter syntax in ruby. I guess the main difference is that the name of the element you're iterating over is left implicit compared to comprehensions, but equivalent to filter. details.select{ |item| item[:qty] != "" } [item for item in details if item.qty != ''] filter(lambda item: item.qty != '', items) I'm curious if the implicitness is cumbersome when you need to do a selection that combines multiple lists. How would you express the third line of the following in ruby? A = range(65,69) B = ['A', 'B', 'C', 'D'] [a for a, b in zip(A, B) if b=='C']

onli 8y ago
My approach would probably be to create the zipped list in the beginning, split it for the comparison and then select the wanted element: A = (65..69).to_a B = ['A', 'B', 'C', 'D'] A.zip(B).select{|x, y| y == 'C' }.map{|x, y| x }
- maksimum 8y ago
  Thanks! That looks equivalent to python without comprehensions. As far as I can tell the difference in the expressiveness of `map/filter/reduce` is mainly about whether you like or don't like comprehensions. Do you have any examples where you believe ruby has cleaner syntax?
  - dragonwriter 8y ago
    > As far as I can tell the difference in the expressiveness of `map/filter/reduce` is mainly about whether you like or don't like comprehensions. Comprehensions don't replace reduce, they are equivalent to a combination of map, filter, and flat_map. The difference is not just about comprehensions, since map/filter/reduce, and friends, in Python are functions, where in Ruby they are methods; so in Python when you can't do it all with comprehensions (reduce, zip, etc.), it's either imperative loops or functional notation (inside-out), while Ruby uses method call notation, which results in operations reading in the order of application.
    - maksimum 8y ago
      Great clarification. You're right, reduce was a typo. I definitely like how method call notations can be read left-to-right rather than inside out. Now I'm curious why python developers decided not to add these 'transformation methods' to all Iterables.