In Ruby, why is the drive called memo in input / reduction methods?

Question

Out of curiosity, why is the battery called memo in injection / contraction methods? Is there any context / story behind its name? Does it actually mean a “memo” or a memo for something?

http://ruby-doc.org/core-2.0/Enumerable.html#method-i-inject

http://ruby-doc.org/core-2.0/Enumerable.html#method-i-reduce

Answer 1

"memo" means in memory that the application uses its entire full iteration to store the intermediate state of the object so that it can be used for the next iteration.

Answer 2

I do not have a reliable source for this application, but I think this is a shorthand for “memory”, since this information is stored between iterations.