From Javascript To Haskell
- 1. JavaScript Haskell 2008-01-24 UJIHISA, Tatsuhiro
- 2. who's this? • ujihisa • Osaka Univ. M2 • Fuzzy Rough Sets • nayutaya - http://www.nayutaya.co.jp • LiveCoding, ldev, Haskell, On Lisp...
- 3. from js to hs
- 4. Ruby natural class-based OO prototype-based JavaScript OO, functional Haskell simple functional
- 5. simplicity • process serially • assignment • loop • implicit cast
- 6. simplicity • process serially • assignment • loop • implicit cast
- 7. no variables var a = 1; var b = function() { return 1 }; a = 1 b = 1
- 8. no re-assignment var a = 1; var a = 2; a = 1 a = 2 -- Multiple declarations of `Main.a'
- 9. var f = function() { var i = 0; return function() { return i++; } }; var g = f(); g(); //=> 0 g(); //=> 1 g(); //=> 2 g(); //=> 3 g(); //=> 4
- 10. principle
- 11. write less code • principle: as possible as you should write less code • development, maintenance, ...always.
- 12. notation
- 13. aaa(bbb(quot;hahahaquot;, 3))); aaa (bbb quot;hahahaquot; 3) aaa $ bbb quot;hahahaquot; 3
- 14. window.addEventListener( quot;loadquot;, function() { alert(quot;aquot;) }) main = putStrLn quot;aquot;
- 15. var f = function(a, b) { return a + b }; f(8, 7) //=> 15 f a b = a + b f 8 7 -- 15
- 16. var f = function(a) { var g = function(b) {...}; return g(a); }; f a = g a where g b = ...
- 17. var fib = function(n) { return (n == 1) ? 1 : (n == 2) ? 1 : fib(n-2) + fib(n-1); }; fib 1 = 1 fib 2 = 1 fib n = fib (n-2) + fib (n-1)
- 18. (function(a) { return a + 1 }) (function(a) { return a + 1 })(3) //=> 4 (a -> a + 1) (a -> a + 1) 3 -- 4
- 19. a + b (+) a b add a b a `add` b
- 21. List Processing Haskell vs JavaScript with prototype.js
- 22. [1, 2, 3].map(function(i) { return i + 1; }) //=> [2, 3, 4] map (i -> i + 1) [1, 2, 3] -- [2, 3, 4]
- 23. [1, 2, 3, 4, 5].first() //=> 1 [1, 2, 3, 4, 5][3] //=> 4 head [1, 2, 3, 4, 5] -- 1 [1, 2, 3, 4, 5] !! 3 -- 4
- 24. $R(1, 10).toArray() //=> [1, 2, ..., 10] $R(1, Infinity).toArray() //... [1..10] [1..]
- 25. head [1..] -- 1 head tail [1..] -- 2 [1..] !! 10 -- 11
- 26. curry
- 27. var f = function(a) { return function(b) { return function(c) { return a + b + c }}}; f(3)(5)(7) //=> 15 f a b c = a + b + c f a b = (c -> a + b + c) f a = (b -> (c -> a + b + c)) f = (a -> (b -> (c -> a + b + c))) f 3 5 7 -- 15
- 28. f a b = a + b f a b = (+) a b f = (+) addOne a = 1 + a addOne a = (+) 1 a addOne = (+) 1 addOne = (1 +) map (1 +) [1, 2, 3]
- 30. tmp = []; [1, 2].each(function(x) { [10, 20].each(function(y) { tmp.push(x + y) }) }); [ x + y | x <- [1, 2], y <- [10, 20]] {x + y|x ∈ X, y ∈ Y }
- 31. tmp = []; $R(1, Infinity).each(function(x) { if (x % 2 == 0 && x < 10) { tmp.push(x) } }); [ x | x <- [1..], x `mod` 2 == 0, x < 10] {x|x ∈ N, x ≡ 0 mod 2, x < 10}
- 32. fib again h (+) fib (tail fib) fib = 1 : 1 : zipWit
- 33. how to use • sudo port install ghc • HotMac :-) • runghc a.hs • ghc a.hs && ./a.out • ghci
- 34. for what? • draft • step up • production
- 35. Monadius
- 36. HSP
- 38. • lazy evaluation • monad • type inference
- 39. thank you!