Terminal character widths

Main.hs

module Main where

import System.Console.ANSI
import System.IO
import Data.List
import Data.Traversable
import Graphics.Text.Width (wcwidth)
import Data.Char
import Data.Foldable
import Text.Printf

isAssigned c =
  case generalCategory c of
    NotAssigned -> False
    Surrogate   -> False
    Control     -> False
    _           -> True

main :: IO ()
main =
  withFile "output.txt" WriteMode $ \h ->
  do hSetBuffering stdout NoBuffering
     for_ ['\0'..] $ \i ->
        hPrint h =<<
          if isAssigned i
            then charWidth i
            else return 1


charWidth :: Char -> IO Int
charWidth c =
  do printf "\r%06x: " (ord c)
     putChar c
     Just (_row, col) <- getCursorPosition0
     return (col - 8)

widths.cabal

cabal-version:       2.4
name:                widths
version:             0.1.0.0
license:             ISC
license-file:        LICENSE
author:              Eric Mertens
maintainer:          emertens@gmail.com
extra-source-files:  CHANGELOG.md

executable widths
  main-is:             Main.hs
  build-depends:       base ^>=4.12.0.0, ansi-terminal ^>=0.10, vty ^>=5.25.1
  default-language:    Haskell2010