The name of the function method, which is dual to reduce or inject.

For convolution functions, various names are used for each programming language and argument type, such as fold, reduce, inject, etc., but what are the names of the two functions?fold has unfold corresponding (F#, Haskell), but I don't know the name of the function corresponding to reduce, inject.

I asked because I thought it was necessary to find these functions and define them myself.

Supplement:unfold Specifications
Seq.unfold in F# is a function that takes the function f and the initial state s as arguments and returns the sequence; f is a function that returns the sequence as option.
The same goes for Haskell's unfoldr.