module type Full = Base__.Hash_intf.Full
module type S = Base__.Hash_intf.S
module F : functor (Hash : S) -> Full with type hash_value = Hash.hash_value and type state = Hash.state and type seed = Hash.seed
The code of ppx_hash
is agnostic to the choice of hash algorithm that is
used. However, it is not currently possible to mix various choices of hash algorithms
in a given code base.
We experimented with:
Our findings were as follows:
Hence, we are here making the choice of using this Internalhash (that is, Murmur3, the OCaml hash algorithm as of 4.03) as our hash algorithm. It means that the state of the hash function does not need to be preallocated, and makes for simpler use in hash tables and other structures.
include Full with type Full.state = private int and type Full.seed = int and type Full.hash_value = int
fold_<T> state v
incorporates a value v
of type <T> into the hash-state,
returning a modified hash-state. Implementations of the fold_<T>
functions may
mutate the state
argument in place, and return a reference to it. Implementations
of the fold_<T> functions should not allocate.
reset ?seed state
initializes/resets a hash-state with the given seed
, or else a
default-seed. Argument state
may be mutated. Should not allocate.
module For_tests : sig ... end
val of_fold : (state ‑> 'a ‑> state) ‑> 'a ‑> hash_value
of_fold fold
constructs a standard hash function from an existing fold
function.
module Builtin : sig ... end
val run : ?seed:seed ‑> 'a folder ‑> 'a ‑> hash_value
run ?seed folder x
runs folder
on x
in a newly allocated hash-state,
initialized using optional seed
or a default-seed.
The following identity exists: run [%hash_fold: T]
== [%hash: T]
run
can be used if we wish to run a hash-folder with a non-default seed.