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I, too, think like that, although Ruby's nomenclature frequently confuses me. Coming from Scheme/Haskell I'm quite at home with 'map', 'filter', and 'fold'. Ho

I, too, think like that, although Ruby's nomenclature frequently confuses me. Coming from Scheme/Haskell I'm quite at home with 'map', 'filter', and 'fold'. However, Ruby uses the methods you mention, "collect" and "inject", and these in turn have a few synonyms. And as best I can tell, Ruby's 'filter' variant, 'find' collides with ActiveRecord. What's the general community take on these functions? Which name is commonly used, and how do you do filter in Rails?

cdcarter 14y ago
I'd say that most Rubyists use #select, whereas #find is a more literate alias that few use outside of AR.
- yxhuvud 14y ago
  They are not synonyms. Find will only find one result.
philwelch 14y ago
In Ruby, I always use "map" instead of "collect", partially because it's four fewer letters and partially because its intent is a little more obvious.
masklinn 14y ago
> I, too, think like that, although Ruby's nomenclature frequently confuses me. Most of them come from Smalltalk's Iterable protocol[0]: that's the source for `select:aBlock`, `collect:aBlock`, `inject:thisValue into:binaryBlock` (Smalltalk uses `fold` when there's no starting value, and `inject` as "fold by injecting initial value"), `detect:aBlock` and `reject:aBlock`. Smalltalk also uses `do:aBlock` where Ruby uses `each`, likely due to `do` being a keyword in Ruby. Also, `find` is not `filter` (that's `select`, aliased to `find_all`). `find` is also `find` in Haskell[1] (and maps to Smalltalk's `detect`, also useable in Ruby). > 'find' collides with ActiveRecord Uh... no, ActiveRecord collides with Enumerable, I'm pretty damn sure Enumerable came first. > how do you do filter in Rails? What's wrong with #find? Or #where? Or #find_by_*? Same name, different namespace, different meaning. Kind-of the point. [0] http://www.gnu.org/software/smalltalk/manual-base/html_node/Iterable_002denumeration.html#Iterable_002denumeration http://www.gnu.org/software/smalltalk/manual-base/html_node/... [1] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-List.html#v:find http://hackage.haskell.org/packages/archive/base/latest/doc/...

cdcarter 14y ago

I'd say that most Rubyists use #select, whereas #find is a more literate alias that few use outside of AR.

yxhuvud 14y ago
They are not synonyms. Find will only find one result.

philwelch 14y ago

In Ruby, I always use "map" instead of "collect", partially because it's four fewer letters and partially because its intent is a little more obvious.

masklinn 14y ago

> I, too, think like that, although Ruby's nomenclature frequently confuses me. Most of them come from Smalltalk's Iterable protocol[0]: that's the source for `select:aBlock`, `collect:aBlock`, `inject:thisValue into:binaryBlock` (Smalltalk uses `fold` when there's no starting value, and `inject` as "fold by injecting initial value"), `detect:aBlock` and `reject:aBlock`. Smalltalk also uses `do:aBlock` where Ruby uses `each`, likely due to `do` being a keyword in Ruby. Also, `find` is not `filter` (that's `select`, aliased to `find_all`). `find` is also `find` in Haskell[1] (and maps to Smalltalk's `detect`, also useable in Ruby). > 'find' collides with ActiveRecord Uh... no, ActiveRecord collides with Enumerable, I'm pretty damn sure Enumerable came first. > how do you do filter in Rails? What's wrong with #find? Or #where? Or #find_by_*? Same name, different namespace, different meaning. Kind-of the point. [0] http://www.gnu.org/software/smalltalk/manual-base/html_node/Iterable_002denumeration.html#Iterable_002denumeration http://www.gnu.org/software/smalltalk/manual-base/html_node/... [1] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-List.html#v:find http://hackage.haskell.org/packages/archive/base/latest/doc/...