src/signatures.ml

@@ -4,6 +4,17 @@
    check endianness
 
    better handling of decoding failure *)
+
+type one
+type two
+
+type (_, _) typ =
+  | R : 'r -> ('r, one) typ
+  | Sig : string -> ('r, two) typ
+
+let sign : type r. (r -> string) -> (r, one) typ -> (r, two) typ =
+ fun f (R r) -> Sig (f r)
+
 open Hash
 
 module Aliases = struct