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Notty — Declaring terminals

Notty is a declarative terminal library for OCaml structured around a notion of composable images. It tries to abstract away the basic terminal programming model, providing something simpler and more expressive.

The core layout engine and IO codecs are pure platform-independent OCaml. Distribution includes modules with input and output facilities for Unix, and Lwt on Unix.

As an attempt to redefine terminal programming, Notty has to be opinionated. It assumes Unicode throughout, does not have universal support for various terminals out there, and has a peculiar programming and rendering model.

Notty's core API was heavily influenced by Haskell's Vty.

Where to start

Check out the documentation, examples, or peek directly into the interface file.

Building with dune build @ex will produce several little example programs that also double as tests.

(* Game of Life with ZX Spectrum kitsch. *)

let dot : image = I.uchar A.(fg lightred) (Uchar.of_int 0x25cf) 1 1

let background step (n, m) =
  let k = 24. *. sin (float (step + m + n) /. 10.) |> truncate in
  if k > 0 then I.char A.(fg (gray k)) '.' 1 1 else I.void 1 1

let render (w, h) step life : image =
  I.tabulate w (h - 1) @@ fun x y ->
    let pt = (x, y) in
    if CSet.mem pt life then dot else background step pt


  • Notty?

    Terminals are tedious to program for. Notty tries to abstract the tedium away, leaving you with a more pleasant programming surface that's quite unlike a TTY. Hence, No-TTY.

  • A new kind of Rust terminal?

    This Notty has no connection to any other body of code named Notty.

  • Why make yet another terminal output library?


    • It allows one to describe what should be seen, as opposed to commanding a terminal.
    • It's pretty compact. Both bells and whistles can be implemented separately.
    • Core is easy to glue onto various IO backends.
    • Pure platform-independent OCaml.


Declarative terminal graphics for OCaml







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