A high-level ncurses alternative written in Haskell
Haskell C Other
Latest commit 7448ab8 Dec 26, 2016 @jtdaugherty committed on GitHub Merge pull request #118 from diegospd/patch-1
Fixed typo wiht -> with
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cbits Revert "Replace stale wcwidth implementation with utf8proc library call" Nov 19, 2016
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docs - Nov 7, 2009
scripts refactor vty to use standard naming convention. Apr 12, 2014
src Fixed typo wiht -> with Dec 26, 2016
test Fix config test Sep 2, 2016
.gitignore Allow 'empty' text images and relax constraints on joining clipped im… Dec 3, 2016
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AUTHORS up to 5.2.3 for release Sep 25, 2014
CHANGELOG Update changelog, bump version Dec 4, 2016
DESIGN adding example of Graphics.Vty.Inline to test Dec 28, 2009
Demo.hs Fixup how the standardIOConfig is applied. Correct the Config Monoid. #… Aug 9, 2015
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ModeDemo.hs ModeDemo: import Control.Applicative explicitly Jun 26, 2016
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Setup.lhs use alloca instead of mallocBytes for exception safety Sep 4, 2009
TODO adding example of Graphics.Vty.Inline to test Dec 28, 2009
build_examples add a build examples script which just builds the examples package Nov 13, 2013
install_examples rename ClassifyTable to ClassifyTableV1 Nov 18, 2013
stack.yaml Add stack.yml project definition May 11, 2016
view-benchmark-core add view-benchmark-core to use ghc-core to view the full core of the … Feb 3, 2014
vty.cabal Raise base lower bound and disable GHC allowed-failing build as sugge… Dec 12, 2016


Build Status

vty is a terminal interface library.

This project is hosted on github.com: https://github.com/jtdaugherty/vty

Install via git with:

git clone git://github.com/coreyoconnor/vty.git

Install via cabal with:

cabal install vty


  • Support for a large number of terminals. vt100, ansi, hurd, linux, screen etc etc. Anything with a sufficient terminfo entry.

  • Automatic handling of window resizes.

  • If the terminal support UTF-8 then vty supports Unicode output.

  • Handles multi-column glyphs. (Requires user to properly configure terminal.)

  • Efficient output. Output buffering and terminal state changes are minimized.

  • Minimizes repaint area. Virtually eliminating the flicker problems that plagues ncurses programs.

  • A pure, compositional interface for efficiently constructing display images.

  • Automatically decodes keyboard keys into (key,[modifier]) tuples.

  • Automatically supports refresh on Ctrl-L.

  • Automatically supports timeout after for lone ESC. The timeout is customizable.

  • Interface is designed for easy compatible extension.

  • Supports ANSI graphics modes (SGR as defined in console_codes(4)) with a type-safe interface. Gracefull fallback for terminals that do not support, or partially support the standard ANSI graphics modes.

  • Properly handles cleanup, but not due to signals.

  • Comprehensive test suite.

Known Issues

  • Terminals have numerous quirks and bugs. vty picks what works best for the author in ambigious, or buggy situations.

  • Signal handling of STOP, TERM and INT are non existent.

  • The character encoding of the terminal is assumed to be UTF-8 if unicode is used.

  • Terminfo is assumed to be correct unless there is an override configured. Some terminals will not have correct special key support (shifted F10 etc). See Config for customizing vty's behavior for a particular terminal.

  • Uses the TIOCGWINSZ ioctl to find the current window size, which appears to be limited to Linux and BSD.

  • Supports "normal" and "extended" (SGR) mouse modes as described at http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-Mouse-Tracking

  • Supports bracketed paste mode as described at http://cirw.in/blog/bracketed-paste

Platform Support

Posix Terminals

Uses terminfo to determine terminal protocol. With some special rules to handle some omissions from terminfo.


cygwin only.

Development Notes

Under NixOS

Using cabal

After installing ncurses to user env.

LIBRARY_PATH=$HOME/.nix-profile/lib/ cabal configure --enable-tests --extra-lib-dirs=$HOME/.nix-profile/lib
LIBRARY_PATH=$HOME/.nix-profile/lib/ cabal build
LIBRARY_PATH=$HOME/.nix-profile/lib/ cabal test

Using stack

stack build
stack test
stack install


As of last testing, profiling causes issues with coverage when enabled. To evaluate coverage configure as follows:

rm -rf dist ; cabal configure --enable-tests --enable-library-coverage \
  --disable-library-profiling \


rm -rf dist ; cabal configure --enable-tests --disable-library-coverage \
  --enable-library-profiling \