Why is Ruby's Array.map() also called Array.collect()?

Question

Whenever I see Ruby code that says:

arrayNames.collect { ... }

I forget what collect is and have to look up what it is, and find that it is the same as map().

Map, I can understand, mapping 1 byte to a pixel, and function is to map an x to a y, a 2 to a 4, a 5 to a 25, etc. But where does the name "collect" come from? Maybe that will help to remember what a "collect" method is.

Answer 1

It comes from Smalltalk old days. Smalltalk used collect and select instead of map and filter (as used in many other languages) for iterating on its collections.

Answer 2

kriss is right that the method name has its origins in Smalltalk but to help remember what it does when you see it used you can think of it as "collecting the results from the block in a new array".

Answer 3

To add to the other answers, it is kind of an inside-joke in Smalltalk:

• inject:into:
• collect:
• select:
• reject:
• detect:

Spot the pattern?