計算機科学のブログ

name:                lesson
version:             0.1.0.0
github:              "githubuser/lesson"
license:             BSD3
author:              "Author name here"
maintainer:          "example@example.com"
copyright:           "2022 Author name here"

extra-source-files:
- README.md
- ChangeLog.md

# Metadata used when publishing your package
# synopsis:            Short description of your package
# category:            Web

# To avoid duplicated efforts in documentation and dealing with the
# complications of embedding Haddock markup inside cabal files, it is
# common to point users to the README.md file.
description:         Please see the README on GitHub at <https://github.com/githubuser/lesson#readme>

dependencies:
- base >= 4.7 && < 5
- bytestring
- text

library:
  source-dirs: src

executables:
  lesson-exe:
    main:                Main.hs
    source-dirs:         app
    ghc-options:
    - -threaded
    - -rtsopts
    - -with-rtsopts=-N
    dependencies:
    - lesson

tests:
  lesson-test:
    main:                Spec.hs
    source-dirs:         test
    ghc-options:
    - -threaded
    - -rtsopts
    - -with-rtsopts=-N
    dependencies:
    - lesson

default-extensions: OverloadedStrings

module Main where

import qualified Data.ByteString as B
import qualified Data.Text as T
import qualified Data.Text.Encoding as E
import Lib

main :: IO ()
main = do
  -- args <- getArgs
  -- let fileName = head args
  let fileName = "hello.txt"
  bytes <- B.readFile fileName
  putStrLn $
    mconcat
      [ "文字数: ",
        show $ T.length $ E.decodeUtf8 bytes
      ]
  putStrLn $
    mconcat
      [ "バイト数: ",
        show $ B.length bytes
      ]

% cat hello.txt 
Hello, 世界!%                                                                   % wc hello.txt 
       0       2      14 hello.txt
% stack exec lesson-exe
文字数: 10
バイト数: 14
%