Accumulate with init

General Usage
1

Just noticed that accumulate does not include its init value in the output vector. What is the reason for that choice?

Including init would be handy for cases like:

v = rand(10)
accumulate(+, diff(v); init = v[1])

It would also match scanl in Haskell. There it’s motivated as scanl f e = map (foldl f e) . inits where inits computes all prefixes (starting with the empty one).

2

Ok, have checked a few more languages and there does not seem to be much consistency:

  • Inluding init: Haskell scanl, Clojure reductions, R Reduce with accumulate = T

  • Excluding init: Rust scan, Julia accumulate, J F:.