4 files changed, 22 insertions, 2 deletions
diff --git a/lib/concepts/Hash.ml b/lib/concepts/Hash.ml
index 922851a..5f023fc 100644
--- a/lib/concepts/Hash.ml
+++ b/lib/concepts/Hash.ml
@@ -11,6 +11,11 @@ let hash_of_bytes bytes = Digestif.SHA256.digest_bytes bytes
 
 let hash_of_blob blob = Blob.bytes_of_blob blob |> Digestif.SHA256.digest_bytes
 
+let hash_of_int i =
+  let b = Blob.create 8 in
+  Blob.set_int64_be b 0 (Int64.of_int i);
+  hash_of_blob b
+
 let bytes_of_hash (h : hash) = Bytes.of_string (Digestif.SHA256.to_raw_string h)
 
 let blob_of_hash h = bytes_of_hash h |> Blob.blob_of_bytes
diff --git a/lib/concepts/Hash.mli b/lib/concepts/Hash.mli
index ca50406..256f3cd 100644
--- a/lib/concepts/Hash.mli
+++ b/lib/concepts/Hash.mli
@@ -4,12 +4,15 @@ type hash
 (** the size of a hash, in bytes *)
 val size : int
 
-(** given a bag of bytes, compute it's hash *)
+(** given a bag of bytes, compute its hash *)
 val hash_of_bytes : bytes -> hash
 
-(** given a blob, compute it's hash *)
+(** given a blob, compute its hash *)
 val hash_of_blob : Blob.t -> hash
 
+(** given an int, compute its hash *)
+val hash_of_int : int -> hash
+
 (** given a hash, return a representation of it as a string (/not/ the usual hex representation!) *)
 val to_raw_string : hash -> string
 
diff --git a/lib/kernel/Identity.ml b/lib/kernel/Identity.ml
new file mode 100644
index 0000000..ce3d30c
--- /dev/null
+++ b/lib/kernel/Identity.ml
@@ -0,0 +1,7 @@
+class type identity = object
+  method hash : Concepts.Hash.hash
+end
+
+class of_id = object (self)
+  method hash = Oo.id self |> Concepts.Hash.hash_of_int
+end
diff --git a/lib/kernel/Identity.mli b/lib/kernel/Identity.mli
new file mode 100644
index 0000000..cdf417c
--- /dev/null
+++ b/lib/kernel/Identity.mli
@@ -0,0 +1,5 @@
+class type identity = object
+  method hash : Concepts.Hash.hash
+end
+
+class of_id : identity