2008-01-25 tangible value
TRANSCRIPT
Tangible Valuein Haskell
1Friday, January 25, 2008
•http://www.youtube.com/watch?v=faJ8N0giqzw
•http://conal.net/papers/Eros/
•http://journal.conal.net/#[[separating IO from logic -- example]]
•http://conal-elliott.blogspot.com/search/label/TV
Conal Elliott
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Eros3Friday, January 25, 2008
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applications:
1. user-friendly2. usable3. concrete4. visual
libraries:
1. programmer-friendly2. composable3. abstract4. syntactic
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•Write programs that do one thing and do it well
•Write programs to work together
•Write programs to handle text streams, because that is a universal interface
UNIX philosophy
Doug McIlroy
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godfat ~/p/l/l/l/proc> ls | sort | cat -n 1 bind.rb 2 chain.rb 3 compose.rb 4 curry.rb
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TV8Friday, January 25, 2008
原始程式
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module Grading where
import Data.List (sort)import Data.Map (Map,empty,keys,insertWith,findWithDefault)import Text.Printf
import Interface.TVimport Interface.TV.OFun() -- work around GHC bug. ticket #1145
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grades = do src <- readFile "tasks" let pairs = map (split.words) (lines src) grades = foldr insert empty pairs mapM_ (draw grades) (sort (keys grades)) where insert (s, g) = insertWith (++) s [g] split [name,mark] = (name, read mark) draw g s = printf "%s\t%s\tAverage: %f\n" s (show marks) avg where marks = findWithDefault (error "No such student") s g avg = sum marks / fromIntegral (length marks) :: Double
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抽出I/O
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gradingStr src = concatMap (draw grades) (sort (keys grades)) where pairs = map (split.words) (lines src) grades = foldr insert empty pairs insert (s, g) = insertWith (++) s [g] split [name,mark] = (name, read mark) draw g s = printf "%s\t%s\tAverage: %f\n" s (show marks) avg where marks = findWithDefault (error "No such student") s g avg = sum marks / fromIntegral (length marks) :: Double
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type GradingStr = String -> StringgradingStr :: GradingStr
grades_2 = readFile "tasks" >>= return . gradingStr >>= putStr
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inTV
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type GradingStr = String -> StringgradingStr :: GradingStr
grades_2 = readFile "tasks" >>= return . gradingStr >>= putStr
gradingStrOut = oLambda (fileIn "tasks") stringOutgradingStrT :: TV KIO GradingStrgradingStrT = tv gradingStrOut gradingStr
grades_3 = runTV gradingStrT
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Eros17Friday, January 25, 2008
(1)18Friday, January 25, 2008
視覺化19Friday, January 25, 2008
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(2)24Friday, January 25, 2008
融合25Friday, January 25, 2008
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first :: (a -> a') -> ((a, b) -> (a',b ))second :: (b -> b') -> ((a, b) -> (a ,b'))result :: (b -> b') -> ((a->b) -> (a->b'))
first f = \ (a, b) -> (f a, b)second g = \ (a, b) -> ( a, g b)result g = \ f -> g . f
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sf :: (b->b') -> (a,(b ,c)) -> (a,(b',c))
sf = second.first
frsrf :: (c->c') -> (a->(f,b->(c ,g)),e) -> (a->(f,b->(c',g)),e)
frsrf = first.result.second.result.first
funFirst :: (d -> (c->a)) -> ((d,b) -> (c->(a,b)))
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(3)31Friday, January 25, 2008
MV分離
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type TV a = (Out a, a)
type Out a = ...put :: Put a -> Out aopair :: Out a -> Out b -> Out (a, b)olambda :: In a -> Out b -> Out (a->b)
type In a = ...get :: Get a -> In aipair :: In a -> In b -> In (a,b)
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•TypeCompose
•DeepArrow
•DataDriven
•Phooey
Eros
•TV
•GuiTV
•wxHaskell
•wxWidgets
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•Tangible polymorphism?
•Direct structural tweaks
•Symmetric In/Out (ilambda)
•“GUIs are types” as GUI design guide
•TVs as composable MVC
To explore
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