Treats the grid as a grid of one- dimensional grids such that the same operation (here addition) will be performed on all its elements together with the base value. the results are combined back. each #fold operation removes a dimension. syntax: #fold
some other forms:
[#fold +] computes totals
[#fold inv+] is an alternated sum (+/-)
[#fold *] can compute the size of a grid using its dimension list
[#fold &] can mean "for all"
[#fold |] can mean "there exists (at least one)"
[#fold ^] can mean "there exists an odd number of..."
the operator to fold with.
Outputs a grid that has one less dimension than the input.
the initial value for the folding. (default: none)
this can be a grid of any size, and this decides the size of the subgrids we are working on: a seed that has N dimensions will cause the folding to happen on the dimension that is just before the last N dimensions.
replaces every subgrid (of one or more dimensions) by the result of a cascade on that subgrid. Doing that with seed value 0 and operation + on grid "2 3 5 7" will compute ((((0+2)+3)+5)+7) find the total "17".