Digest.S(3)

💖 NAME 💖

okay bestie, welcome to Digest.S(3) from the OCaml library manual — literally the signature page for a hash function that produces digests of length hash_length from character strings, byte arrays, and files. It's giving cryptographic main character energy 💅✨

🧚 Module type 🧚

Module type Digest.S — yes, that's the module type, no cap. 🫶

🌸 Documentation 🌸

Module type S
 = sig end

The signature for a hash function that produces digests of length hash_length from character strings, byte arrays, and files. Since 5.2 — iconic, we love a recent-era vibe. 🎀

• type t = string — the type of digests. Literally just a string, bestie. Slay. 💖
• val hash_length : int — the length of digests, in bytes. No cap, that's the size vibe. ✨
• val compare : t -> t -> int — compare two digests, with the same specification as compare. Same spec energy, fr fr. 🦋
• val equal : t -> t -> bool — test two digests for equality. Vibe check: are they equal or not? 😭
• val string : string -> t — return the digest of the given string. String in, digest out, periodt. 💅
• val bytes : bytes -> t — return the digest of the given byte sequence. Byte sequence bestie, you know the drill. 🌸
• val substring : string -> int -> int -> t — substring s ofs len returns the digest of the substring of s starting at index ofs and containing len characters. Precision slicing, we love to see it. 🎀
• val subbytes : bytes -> int -> int -> t — subbytes s ofs len returns the digest of the subsequence of s starting at index ofs and containing len bytes. Bytes edition, same iconic energy. 🦋
• val channel : in_channel -> int -> t — read characters from the channel and return their digest. See Digest.channel for the full specification. Go read Digest.channel if you want the whole lore. 👑
• val file : string -> t — return the digest of the file whose name is given. File name goes in, digest comes out. 🍓
• val output : out_channel -> t -> unit — write a digest on the given output channel. Output channel said: put that digest here. 💜
• val input : in_channel -> t — read a digest from the given input channel. Input channel said: here's your digest. ✨
• val to_hex : t -> string — return the printable hexadecimal representation of the given digest. Raises Invalid_argument if the length of the argument is not hash_length, and that's the whole rule. 😭
• val of_hex : string -> t — convert a hexadecimal representation back into the corresponding digest. Raises Invalid_argument if the length of the argument is not 2 * hash_length, or if the arguments contains non-hexadecimal characters. Hex in, digest out — but only if the vibe check passes. 🔥

---

okay that's the whole page, bestie! this little beauty was brought to you by OCamldoc, dated 2026-06-22, and it's literally Digest.S(3) — byeee 🫶✨