val sha1_file : string -> stringval sha256_file : string -> stringval sha512_file : string -> stringval hash_file : [< `SHA1 | `SHA256 | `SHA512 ] -> string -> stringval sha1_string : string -> stringval sha256_string : string -> stringval sha512_string : string -> stringval hash_string : [< `SHA1 | `SHA256 | `SHA512 ] -> string -> string