Functional Programming

1
PROGRAMMING IN HASKELL ???????Haskell
Chapter 9 - Interactive Programs ???????
?????? ????? ??????(???????????2011?)????
?????? http//www.cs.nott.ac.uk/gmh/book.html
??????
2
Introduction
8 ????Haskell ????????????????????????????????????
?????????????????????
3
????Haskell ??????????????????????????????????????
?????????????????????????
4
???
Haskell ???????????????????

• Haskell ??????????(side effect)?????

???????????????????????????????

• ???????????????

5
???
Haskell ??????????????????????????????????????????
??????
IO a
? a ????????????
6
For example
????????????
IO Char
?????????? ???????????
IO ()
Note

• () ????????????(????????? p.23)

7
???????
??????????? 3 ????????????????????????

• ????? getChar ????????? 1 ????????????????????????
  ??????????

getChar IO Char
8

• ????? purChar c ???? c ?????????????????

putChar Char ? IO ()

• ????? return v ?????????????? v ???

return a ? IO a
9
???????(???Sequencing)
8 ?? do ???????
?????????????????? do ???? ?????????????????????
?
a IO (Char,Char) a do x ? getChar
getChar y ? getChar return (x,y)
10
?????????????

• ??????? 1 ?????

getLine IO String getLine do x ? getChar
if x '\n' then
return else do
xs ? getLine return (xxs)
11

• ??????????????

putStr String ? IO () putStr
return () putStr (xxs) do putChar x
putStr xs

• ??????????????????

putStrLn String ? IO () putStrLn xs do
putStr xs putChar '\n'
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Example
????????????????????????? ???????????????
strlen IO () strlen do putStr "Enter a
string " xs ? getLine
putStr "The string has " putStr
(show (length xs)) putStrLn "
characters"
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For example
gt strlen Enter a string abcde The string has 5
characters
Note
?????????????????????????????????????
14
????????????????????????????
15
Hangman
????????????????????

• ??????????????????
• ?????????????????????
• ??????????????????????????????????????????
• ??????????????

16
Haskell?????????????????????????????????????????
hangman IO () hangman do putStrLn "Think
of a word " word ? sgetLine putStrLn
"Try to guess it" guess word
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????? sgetLine ?????????????????????????? 1
???????????
sgetLine IO String sgetLine do x ? getCh
if x '\n' then
do putChar x return
else do putChar '-'
xs ? sgetLine
return (xxs)
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Note

• ????? getCh ???????? 1 ????????????????????????
• ???????????????????????Hugs ??????????????????????
  ??????

primitive getCh IO Char
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?? guess ??????????????????? ????????????????????
guess String ? IO () guess word do
putStr "gt " xs ? getLine if xs
word then putStrLn "You got it!"
else do putStrLn (diff word xs)
guess word
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?? diff ??1 ??????????????2 ?????????????????
diff String ? String ? String diff xs ys
if elem x ys then x else '-' x ? xs
?
gt diff "haskell" "pascal" "-as--ll"
21
???(9?)

• Haskell ??
• ???? ?????
• ?????? ???????????? IO a ?? a ??????????
• IO Char ????????????
• IO () ???????????????
• ????????
• getChar IO Char 1 ???????????????
• putChar Char -gt IO () 1 ??????????
• return v a -gt IO a ?????????? v ???
• getLine IO String ???????????????
• putStr String -gt IO () ????????? (putStrLn
  ?????)
• ?????????????????
• do x ? p1 p2 y ? pn (??)

22
????(9?)

• ??? p.109 ? strlen ?????????????
• ??????????????????????????????
• Hangman.hs ??? Web ??????????http//www.ist.aichi
  -pu.ac.jp/lab/yamamoto/program_languages/2011/
• ?????????????????????????????????????????????????
• ????????????????

23
??????(Linux)

• http//www.cs.nott.ac.uk/gmh/book.html ? Code
  ??????????????????
• calculator.lhs (Calculator, 9.6 ???)
• life.lhs (Game of life, 9.7 ?)
• Parsing.lhs (Functional parsing library, 8 ????)
• calculator.lhs ? Parsing.lhs ????????????
• calculator.lhs ? Parsing.lhs ? import ??????
• Linux ?? ghci ????????
• calculator.lhs ??????run ??????????????????????
• life.lhs ?????? life glider ??????????????????????
  ????

24
??????(Windows, ??1)

• http//www.cs.nott.ac.uk/gmh/book.html ? Code
  ??????????????????
• Parsing.lhs (Functional parsing library, 8 ????)
• http//www.ist.aichi-pu.ac.jp/lab/yamamoto/program
  _languages/ ? 2011 ??????????????????????
• calculatoWin.lhs (Calculator, 9.6 ???)
• lifeWin.lhs (Game of life, 9.7 ?)
• calculatorWin.lhs ? Parsing.lhs ????????????
• calculatorWin.lhs ? Parsing.lhs ? import ??????

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??????(Windows, ??2)

• ansi-terminal ?????????
• cabal ? Haskell Platform ?????????
• ??????????????
• ?????????????? cabal update
• ansi-terminal ????????? cabal install
  ansi-terminal
• Windows ? GHCi ????????
• ??????WinGHCi ??????
• calculatorWin.lhs ??????run ??????????????????????
  
• lifeWin.lhs ?????? life glider ???????????????????
  ???????

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????
Nim ??????? Haskell ???????????????????

• ????????? 5 ???????

1 2 3 4 5
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• 2 ???????????????? 1 ????????????? 1 ??????????
• ??????????????????

??? ??????????????????????? 5 ???????????????
????????? 5,4,3,2,1 ????