A module internal to Incremental. Users should see Incremental_intf.

An `Array_fold.t` is a kind of DAG node. It is an immutable value that holds the children of type `'a` and can `compute` the fold to produce a value of type `'b`.

`include module type of sig ... end`
`type ('a, 'acc) t``= ('a, 'acc) Incremental_kernel__Types.Array_fold.t``=` `{`

`init : 'acc;`
`f : 'acc ‑> 'a ‑> 'acc;`
`children : 'a Incremental_kernel__Types.Node.t array;`

`}```
`include Incremental_kernel__.Sexp_of.S2 with type (a, b) t := (a, b) t`
`type ('a, 'b) t`````
`include sig ... end`
`val sexp_of_t : ('a ‑> Base.Sexp.t) ‑> ('b ‑> Base.Sexp.t) ‑> ('a, 'b) t ‑> Base.Sexp.t`
`include Core_kernel.Invariant.S2 with type (a, b) t := (a, b) t`
`type ('a, 'b) t`````
`val invariant : 'a Base__.Invariant_intf.inv ‑> 'b Base__.Invariant_intf.inv ‑> ('a, 'b) t Base__.Invariant_intf.inv`
`val compute : (_, 'b) t ‑> 'b`