tty#

Terminal styling and layout widgets for OCaml CLI applications.

╭──────────────────────────────────────────────────────────────────╮
│                                                                  │
│   ████████╗████████╗██╗   ██╗                                    │
│   ╚══██╔══╝╚══██╔══╝╚██╗ ██╔╝                                    │
│      ██║      ██║    ╚████╔╝                                     │
│      ██║      ██║     ╚██╔╝                                      │
│      ██║      ██║      ██║                                       │
│      ╚═╝      ╚═╝      ╚═╝                                       │
│                                                                  │
│   Type-safe terminal styling and layout widgets for OCaml        │
│                                                                  │
╰──────────────────────────────────────────────────────────────────╯

What it looks like#

Tables#

╭──────────┬────────┬─────────┬──────────┬─────────┬───────────╮
│ Target   │ Inst.  │ Execs   │ Paths    │ Crashes │ Exec/s    │
├──────────┼────────┼─────────┼──────────┼─────────┼───────────┤
│ cbort    │      3 │    1.2M │      847 │       0 │     4,521 │
│ yamlrw   │      3 │    890K │    1,203 │       2 │     3,102 │
│ jsonwt   │      2 │    2.1M │      412 │       0 │     6,847 │
╰──────────┴────────┴─────────┴──────────┴─────────┴───────────╯

Trees#

src
├── lib
│   ├── tty.ml
│   ├── style.ml
│   └── table.ml
├── bin
│   └── main.ml
└── test
    └── test_tty.ml

Panels#

╭─────────────────────── Status ───────────────────────╮
│                                                      │
│  ✓ All systems operational                           │
│  ✓ Database connected                                │
│  ✓ Cache warmed                                      │
│                                                      │
╰──────────────────────────────────────────────────────╯

Border Styles#

ASCII:            Single:           Rounded:          Heavy:
+-------+         ┌───────┐         ╭───────╮         ┏━━━━━━━┓
| hello |         │ hello │         │ hello │         ┃ hello ┃
+-------+         └───────┘         ╰───────╯         ┗━━━━━━━┛

Double:
╔═══════╗
║ hello ║
╚═══════╝

Features#

• Composable styles: Style.(bold + fg Color.red + underline)
• Full color support: ANSI 16, 256-color palette, true color (RGB/hex)
• Tables: Headers, alignment, multiple border styles
• Trees: Directory-style tree rendering with guides
• Panels: Bordered boxes with titles
• Unicode-aware: Proper width calculation for CJK and emoji

Installation#

opam install tty

Quick Start#

Styled Text#

open Tty

(* Compose styles with + *)
let success = Style.(bold + fg Color.green)
let error = Style.(bold + fg Color.red)
let warning = Style.(fg Color.yellow)

let () =
  Fmt.pr "%a@." (Style.styled success Fmt.string) "✓ Build passed";
  Fmt.pr "%a@." (Style.styled error Fmt.string) "✗ Tests failed";
  Fmt.pr "%a@." (Style.styled warning Fmt.string) "⚠ Deprecation warning"

Tables#

open Tty

let () =
  let table = Table.(
    of_rows ~border:Border.rounded
      [ column "Name"; column ~align:`Right "Size"; column "Modified" ]
      [
        [ Span.text "README.md"; Span.text "2.4K"; Span.text "2 hours ago" ];
        [ Span.text "src/"; Span.text "4.0K"; Span.text "yesterday" ];
        [ Span.text "Makefile"; Span.text "892"; Span.text "3 days ago" ];
      ]
  ) in
  Table.pp Format.std_formatter table

Output:

╭───────────┬──────┬─────────────╮
│ Name      │ Size │ Modified    │
├───────────┼──────┼─────────────┤
│ README.md │ 2.4K │ 2 hours ago │
│ src/      │ 4.0K │ yesterday   │
│ Makefile  │  892 │ 3 days ago  │
╰───────────┴──────┴─────────────╯

Trees#

open Tty

let () =
  let tree = Tree.of_tree (
    Node (Span.text "myproject", [
      Node (Span.text "src", [
        Node (Span.text "main.ml", []);
        Node (Span.text "lib.ml", []);
      ]);
      Node (Span.text "test", [
        Node (Span.text "test_main.ml", []);
      ]);
      Node (Span.text "dune-project", []);
    ])
  ) in
  Tree.pp Format.std_formatter tree

Output:

myproject
├── src
│   ├── main.ml
│   └── lib.ml
├── test
│   └── test_main.ml
└── dune-project

Panels#

open Tty

let () =
  let panel = Panel.create
    ~border:Border.rounded
    ~title:(Span.text "Summary")
    (Span.text "Processed 1,234 files\nFound 42 issues\nFixed 38 automatically")
  in
  Panel.pp Format.std_formatter panel

Output:

╭─────────────────────── Summary ────────────────────────╮
│ Processed 1,234 files                                  │
│ Found 42 issues                                        │
│ Fixed 38 automatically                                 │
╰────────────────────────────────────────────────────────╯

Colors#

open Tty

(* ANSI 16 colors *)
let red = Color.red
let bright_blue = Color.bright_blue

(* RGB colors *)
let coral = Color.rgb 255 127 80
let teal = Color.rgb 0 128 128

(* Hex colors *)
let purple = Color.hex "#8B5CF6"
let orange = Color.hex "F97316"

(* 256-color palette *)
let pink = Color.palette 213

(* Use in styles *)
let gradient_style = Style.(fg coral + bg (Color.rgb 30 30 30))

Styles#

Available style attributes:

(* Combine any attributes *)
let fancy = Style.(bold + italic + underline + fg Color.cyan + bg Color.black)

API Reference#

Related Work#

• Rich - Python library for rich text and beautiful formatting. Primary inspiration.
• lipgloss - Go library for terminal styling. Inspiration for composable style API.
• printbox - OCaml library for printing nested boxes, tables and trees.
• progress - Terminal progress bars for OCaml.
• notty - OCaml library for declarative terminal graphics.

Licence#

MIT License. See LICENSE.md for details.