計算機科学のブログ

name:                st-lesson
version:             0.1.0.0
github:              "githubuser/st-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/st-lesson#readme>

dependencies:
- base >= 4.7 && < 5

library:
  source-dirs: src

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

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

module Main where

import Control.Monad (forM_)
import Data.Array.ST (MArray (newArray), runSTUArray, writeArray)
import Data.Array.Unboxed (UArray)

-- import Lib ()

listToUArray :: [Int] -> UArray Int Int
listToUArray vals = runSTUArray $ do
  let end = length vals - 1
  myArray <- newArray (0, end) 0
  forM_ [0 .. end] $ \i -> do
    let val = vals !! i
    writeArray myArray i val
  return myArray

myData :: UArray Int Int
myData = listToUArray [7, 6, 4, 8, 10, 2]

main :: IO ()
main = do
  print myData

% stack runghc app/Main.hs
array (0,5) [(0,7),(1,6),(2,4),(3,8),(4,10),(5,2)]
%