t Prr Pr - PowerPoint PPT Presentation

❋✉♥❝t✐♦♥❛❧ Pr♦❣r❛♠♠✐♥❣ ▼♦♥❛❞✐❝ Pr❡❧✉❞❡ ❏❡✈❣❡♥✐ ❑❛❜❛♥♦✈ ❉❡♣❛rt♠❡♥t ♦❢ ❈♦♠♣✉t❡r ❙❝✐❡♥❝❡ ❯♥✐✈❡rs✐t② ♦❢ ❚❛rt✉

■♥tr♦❞✉❝t✐♦♥ Pr❡✈✐♦✉s❧② ♦♥ ❋✉♥❝t✐♦♥❛❧ Pr♦❣r❛♠♠✐♥❣ ▼♦♥❛❞✐❝ ❧❛✇s ▼♦♥❛❞ ❝❧❛ss ✭ > >= ❛♥❞ r❡t✉r♥ ✮ ▼♦♥❛❞P❧✉s ❝❧❛ss ✭ ♠③❡r♦ ❛♥❞ ♠♣❧✉s ✮ do ✲♥♦t❛t✐♦♥ ▼❛②❜❡ ♠♦♥❛❞ ▲✐st ♠♦♥❛❞ ❙t❛t❡ ♠♦♥❛❞ ■❖ ♠♦♥❛❞

❖✈❡r✈✐❡✇ ▲✐st ❢✉♥❝t✐♦♥s ✶ ❈♦♥❞✐t✐♦♥❛❧s ✷ ▲✐❢t✐♥❣ ✸ ▼♦♥❛❞P❧✉s ❢✉♥❝t✐♦♥s ✹

■♥tr♦❞✉❝t✐♦♥ ❖✈❡r✈✐❡✇ ▼♦♥❛❞ ♣♦✇❡r ❝♦♠❡s ❢r♦♠ ✈❡r② ❤✐❣❤ ❞❡❣r❡❡ ♦❢ ❛❜str❛❝t✐♦♥ ❍❛s❦❡❧❧ ❝♦♠❡s ✇✐t❤ ❛ ❧✐❜r❛r② ♦❢ ❢✉♥❝t✐♦♥s t❤❛t ❛r❡ ❞❡✜♥❡❞ ❛❝r♦ss ❛❧❧ ♠♦♥❛❞s ❚❤❡s❡ ❢✉♥❝t✐♦♥s ❝♦rr❡s♣♦♥❞ t♦ ❝♦♥tr♦❧ str✉❝t✉r❡s ✐♥ ♠♦st ✐♠♣❡r❛rt✐✈❡ ❧❛♥❣✉❛❣❡s ■♥ ❢❛❝t ❣✐✈❡♥ t❤❡ do ✲♥♦t❛t✐♦♥ ❛♥❞ t❤❡s❡ ❢✉♥❝t✐♦♥s ✇❡ ❝❛♥ ♣r♦❣r❛♠ ✐♥ ❍❛s❦❡❧❧ ✉s✐♥❣ ✐♠♣❡r❛t✐✈❡ ❛♣♣r♦❛❝❤

■♥tr♦❞✉❝t✐♦♥ ❖✈❡r✈✐❡✇ ▼♦♥❛❞ ♣♦✇❡r ❝♦♠❡s ❢r♦♠ ✈❡r② ❤✐❣❤ ❞❡❣r❡❡ ♦❢ ❛❜str❛❝t✐♦♥ ❍❛s❦❡❧❧ ❝♦♠❡s ✇✐t❤ ❛ ❧✐❜r❛r② ♦❢ ❢✉♥❝t✐♦♥s t❤❛t ❛r❡ ❞❡✜♥❡❞ ❛❝r♦ss ❛❧❧ ♠♦♥❛❞s ❚❤❡s❡ ❢✉♥❝t✐♦♥s ❝♦rr❡s♣♦♥❞ t♦ ❝♦♥tr♦❧ str✉❝t✉r❡s ✐♥ ♠♦st ✐♠♣❡r❛rt✐✈❡ ❧❛♥❣✉❛❣❡s ■♥ ❢❛❝t ❣✐✈❡♥ t❤❡ do ✲♥♦t❛t✐♦♥ ❛♥❞ t❤❡s❡ ❢✉♥❝t✐♦♥s ✇❡ ❝❛♥ ♣r♦❣r❛♠ ✐♥ ❍❛s❦❡❧❧ ✉s✐♥❣ ✐♠♣❡r❛t✐✈❡ ❛♣♣r♦❛❝❤

■♥tr♦❞✉❝t✐♦♥ ❖✈❡r✈✐❡✇ ▼♦♥❛❞ ♣♦✇❡r ❝♦♠❡s ❢r♦♠ ✈❡r② ❤✐❣❤ ❞❡❣r❡❡ ♦❢ ❛❜str❛❝t✐♦♥ ❍❛s❦❡❧❧ ❝♦♠❡s ✇✐t❤ ❛ ❧✐❜r❛r② ♦❢ ❢✉♥❝t✐♦♥s t❤❛t ❛r❡ ❞❡✜♥❡❞ ❛❝r♦ss ❛❧❧ ♠♦♥❛❞s ❚❤❡s❡ ❢✉♥❝t✐♦♥s ❝♦rr❡s♣♦♥❞ t♦ ❝♦♥tr♦❧ str✉❝t✉r❡s ✐♥ ♠♦st ✐♠♣❡r❛rt✐✈❡ ❧❛♥❣✉❛❣❡s ■♥ ❢❛❝t ❣✐✈❡♥ t❤❡ do ✲♥♦t❛t✐♦♥ ❛♥❞ t❤❡s❡ ❢✉♥❝t✐♦♥s ✇❡ ❝❛♥ ♣r♦❣r❛♠ ✐♥ ❍❛s❦❡❧❧ ✉s✐♥❣ ✐♠♣❡r❛t✐✈❡ ❛♣♣r♦❛❝❤

■♥tr♦❞✉❝t✐♦♥ ❖✈❡r✈✐❡✇ ▼♦♥❛❞ ♣♦✇❡r ❝♦♠❡s ❢r♦♠ ✈❡r② ❤✐❣❤ ❞❡❣r❡❡ ♦❢ ❛❜str❛❝t✐♦♥ ❍❛s❦❡❧❧ ❝♦♠❡s ✇✐t❤ ❛ ❧✐❜r❛r② ♦❢ ❢✉♥❝t✐♦♥s t❤❛t ❛r❡ ❞❡✜♥❡❞ ❛❝r♦ss ❛❧❧ ♠♦♥❛❞s ❚❤❡s❡ ❢✉♥❝t✐♦♥s ❝♦rr❡s♣♦♥❞ t♦ ❝♦♥tr♦❧ str✉❝t✉r❡s ✐♥ ♠♦st ✐♠♣❡r❛rt✐✈❡ ❧❛♥❣✉❛❣❡s ■♥ ❢❛❝t ❣✐✈❡♥ t❤❡ do ✲♥♦t❛t✐♦♥ ❛♥❞ t❤❡s❡ ❢✉♥❝t✐♦♥s ✇❡ ❝❛♥ ♣r♦❣r❛♠ ✐♥ ❍❛s❦❡❧❧ ✉s✐♥❣ ✐♠♣❡r❛t✐✈❡ ❛♣♣r♦❛❝❤

❖✉t❧✐♥❡ ▲✐st ❢✉♥❝t✐♦♥s ✶ ❈♦♥❞✐t✐♦♥❛❧s ✷ ▲✐❢t✐♥❣ ✸ ▼♦♥❛❞P❧✉s ❢✉♥❝t✐♦♥s ✹

▼♦♥❛❞✐❝ Pr❡❧✉❞❡ s❡q✉❡♥❝❡ ❞❡✜♥✐t✐♦♥ s❡q✉❡♥❝❡ ❴ ✿✿ ▼♦♥❛❞ ♠ ✮ ❬ ♠ ❛ ❪ ✦ ♠ ✭✮ s❡q✉❡♥❝❡ ❴ ❂ ❢♦❧❞r ✭ > > ✮ ✭ r❡t✉r♥ ✭✮✮ s❡q✉❡♥❝❡ ✿✿ ▼♦♥❛❞ ♠ ✮ ❬ ♠ ❛ ❪ ✦ ♠ ❬ ❛ ❪ ❂ ❢♦❧❞r ♠❝♦♥s ✭ r❡t✉r♥ ❬ ❪✮ s❡q✉❡♥❝❡ where ♠❝♦♥s ♣ q ❂ ♣ > >= ✕ ① ✦ q > >= ✕ ② ✦ r❡t✉r♥ ✭ ① ✿ ② ✮

s❡q✉❡♥❝❡ s❡q✉❡♥❝❡ ❡①❛♠♣❧❡ Monads> sequence [print 1, print 2, print ’a’] 1 2 ’a’ *Monads> it [(),(),()] *Monads> sequence_ [print 1, print 2, print ’a’] 1 2 ’a’ *Monads> it ()

s❡q✉❡♥❝❡ s❡q✉❡♥❝❡ ❡①❛♠♣❧❡ ✸ Prelude> sequence [Just 1, Just 2, Nothing, Just 3]

s❡q✉❡♥❝❡ s❡q✉❡♥❝❡ ❡①❛♠♣❧❡ ✸ Prelude> sequence [Just 1, Just 2, Nothing, Just 3] Nothing ▼❛②❜❡ ✐s ❛ss②♠♠❡tr✐❝❛❧ ✇✐t❤ r❡s♣❡❝t t♦ ♥♦t❤✐♥❣✦

♠❛♣▼ ♠❛♣▼ ❞❡✜♥✐t✐♦♥ ♠❛♣▼ ✿✿ ▼♦♥❛❞ ♠ ✮ ✭ ❛ ✦ ♠ ❜ ✮ ✦ ❬ ❛ ❪ ✦ ♠ ❬ ❜ ❪ ♠❛♣▼ ❢ ❛s ❂ s❡q✉❡♥❝❡ ✭ ♠❛♣ ❢ ❛s ✮ ♠❛♣▼ ❴ ✿✿ ▼♦♥❛❞ ♠ ✮ ✭ ❛ ✦ ♠ ❜ ✮ ✦ ❬ ❛ ❪ ✦ ♠ ✭✮ ♠❛♣▼ ❴ ❢ ❛s ❂ s❡q✉❡♥❝❡ ❴ ✭ ♠❛♣ ❢ ❛s ✮

♠❛♣▼ ♠❛♣▼ ❡①❛♠♣❧❡ ✶ Monads> mapM_ print [1,2,3,4,5] 1 2 3 4 5 ♠❛♣▼ ❡①❛♠♣❧❡ ✷ ♣✉t❙tr✐♥❣ ✿✿ ❬ ❈❤❛r ❪ ✦ ■❖ ✭✮ ♣✉t❙tr✐♥❣ s ❂ ♠❛♣▼ ❴ ♣✉t❈❤❛r s

❢♦r▼ ❢♦r▼ ❞❡✜♥✐t✐♦♥ ❢♦r▼ ✿✿ ▼♦♥❛❞ ♠ ✮ ❬ ❛ ❪ ✦ ✭ ❛ ✦ ♠ ❜ ✮ ✦ ♠ ❬ ❜ ❪ ❢♦r▼ ❂ ✌✐♣ ♠❛♣▼ ❢♦r▼ ❴ ✿✿ ▼♦♥❛❞ ♠ ✮ ❬ ❛ ❪ ✦ ✭ ❛ ✦ ♠ ❜ ✮ ✦ ♠ ✭✮ ❢♦r▼ ❴ ❂ ✌✐♣ ♠❛♣▼ ❴ ❢♦r▼ ❴ ❡①❛♠♣❧❡ ♠❛✐♥ ❂ do ❢♦r▼ ❴ ❬✶ ✿ ✿ ✶✵❪ ✭ ✕ ✐ ✦ ♣r✐♥t ✐ ✮

☞❧t❡r▼ ☞❧t❡r▼ ❞❡✜♥✐t✐♦♥ ☞❧t❡r▼ ✿✿ ▼♦♥❛❞ ♠ ✮ ✭ ❛ ✦ ♠ ❇♦♦❧ ✮ ✦ ❬ ❛ ❪ ✦ ♠ ❬ ❛ ❪ ☞❧t❡r▼ ♣ ❬ ❪ ❂ r❡t✉r♥ ❬ ❪ ☞❧t❡r▼ ♣ ✭ ① ✿ ①s ✮ ❂ do ❜ ✥ ♣ ① ②s ✥ ☞❧t❡r▼ ♣ ①s r❡t✉r♥ ✭ if ❜ then ✭ ① ✿ ②s ✮ else ②s ✮ ☞❧t❡r▼ ❡①❛♠♣❧❡ ♠❛✐♥ ❂ do ♥❛♠❡s ✥ ❣❡t❆r❣s ❞✐rs ✥ ☞❧t❡r▼ ❞♦❡s❉✐r❡❝t♦r②❊①✐st ♥❛♠❡s ♠❛♣▼ ❴ ♣✉t❙tr▲♥ ❞✐rs

❢♦❧❞▼ ❢♦❧❞▼ ❞❡✜♥✐t✐♦♥ ❢♦❧❞❧ ✿✿ ✭ ❛ ✦ ❜ ✦ ❛ ✮ ✦ ❛ ✦ ❬ ❜ ❪ ✦ ❛ ❢♦❧❞❧ ❢ ③ ❬ ❪ ❂ ③ ❢♦❧❞❧ ❢ ③ ✭ ① ✿ ①s ✮ ❂ ❢♦❧❞❧ ❢ ✭ ❢ ③ ① ✮ ①s ❢♦❧❞▼ ✿✿ ✭ ▼♦♥❛❞ ♠ ✮ ✮ ✭ ❛ ✦ ❜ ✦ ♠ ❛ ✮ ✦ ❛ ✦ ❬ ❜ ❪ ✦ ♠ ❛ ❢♦❧❞▼ ❢ ❛ ❬ ❪ ❂ r❡t✉r♥ ❛ ❢♦❧❞▼ ❢ ❛ ✭ ① ✿ ①s ✮ ❂ ❢ ❛ ① > >= ✕ ② ✦ ❢♦❧❞▼ ❢ ② ①s ◆♦t❡ t❤❛t ✇❡ ❧✐❢t t❤❡ r❡s✉❧t ♦❢ ❛❧❧ ❢✉♥❝t✐♦♥s ✉♥❞❡r t❤❡ ♠♦♥❛❞✳

❢♦❧❞▼ ❢♦❧❞▼ ❡①♣❧❛♥❛t✐♦♥ ❢♦❧❞▼ ❢ ❛✶ ❬ ①✶ ❀ ①✷ ❀ ✿✿✿❀ ①♥ ❪ ❂ do ❛✷ ✥ ❢ ❛✶ ①✶ ❛✸ ✥ ❢ ❛✷ ①✷ ✿✿✿ ❢ ❛♥ ①♥

❢♦❧❞▼ ❢♦❧❞▼ ❡①❛♠♣❧❡ Monads> foldM (\a b -> putStrLn (show a ++ "+" ++ show b ++ "=" ++ show (a+b)) » return (a+b)) 0 [1..5] 0+1=1 1+2=3 3+3=6 6+4=10 10+5=15 Monads> it 15

❢♦❧❞▼ ❢♦❧❞▼ ❡①❛♠♣❧❡ ✷ data ❙❤❡❡♣ ❂ ❙❤❡❡♣ ❢ ♥❛♠❡ ✿✿ ❙tr✐♥❣ ❀ ♠♦t❤❡r ✿✿ ▼❛②❜❡ ❙❤❡❡♣ ❀ ❢❛t❤❡r ✿✿ ▼❛②❜❡ ❙❤❡❡♣ ❣ ❞♦❧❧② ✿✿ ❙❤❡❡♣ ❞♦❧❧② ❂ let ❛❞❛♠ ❂ ❙❤❡❡♣ "Adam" ◆♦t❤✐♥❣ ◆♦t❤✐♥❣ ❡✈❡ ❂ ❙❤❡❡♣ "Eve" ◆♦t❤✐♥❣ ◆♦t❤✐♥❣ ✉r❛♥✉s ❂ ❙❤❡❡♣ "Uranus" ◆♦t❤✐♥❣ ◆♦t❤✐♥❣ ❣❛❡❛ ❂ ❙❤❡❡♣ "Gaea" ◆♦t❤✐♥❣ ◆♦t❤✐♥❣ ❦r♦♥♦s ❂ ❙❤❡❡♣ "Kronos" ✭ ❏✉st ❣❛❡❛ ✮ ✭ ❏✉st ✉r❛♥✉s ✮ ❤♦❧❧② ❂ ❙❤❡❡♣ "Holly" ✭ ❏✉st ❡✈❡ ✮ ✭ ❏✉st ❛❞❛♠ ✮ r♦❣❡r ❂ ❙❤❡❡♣ "Roger" ✭ ❏✉st ❡✈❡ ✮ ✭ ❏✉st ❦r♦♥♦s ✮ ♠♦❧❧② ❂ ❙❤❡❡♣ "Molly" ✭ ❏✉st ❤♦❧❧② ✮ ✭ ❏✉st r♦❣❡r ✮ in ❙❤❡❡♣ "Dolly" ✭ ❏✉st ♠♦❧❧② ✮ ◆♦t❤✐♥❣