2008-01-25 tangible value

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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