Wearing the hair shirt Wearing the hair shirt - Microsoft Research

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Laziness keeps you honest Every call-by-value language has given into <strong>the</strong> siren call of side effects But in Haskell (print “yes”) + (print “no”) just does not make sense. Even worse is [print “yes”, print “no”] So effects (I/O, references, exceptions) are just not an option. Result: prolonged embarrassment. Stream-based I/O, continuation I/O... but NO DEALS WIH THE DEVIL
Monadic I/O A value of type (IO t) is an “action” that, when performed, may do some input/output before delivering a result of type t. eg. getChar :: IO Char putChar :: Char -> IO ()
Page 1 and 2: Wearing the hair shirt A retrospect
Page 3 and 4: Haskell is 15 years old (born FPCA
Page 5 and 6: Timeline Sept 87: kick off Apr 90:
Page 7 and 8: Reflections on the process The i
Page 9: Reflections on process Self-appoin
Page 12 and 13: Syntactic redundancy Seductive ide
Page 14 and 15: “Expression style” Define a fun
Page 16 and 17: Example (ICFP02 prog comp) Pattern
Page 18 and 19: What really matters?
Page 20 and 21: But... Laziness makes it much, muc
Page 22: Combinator libraries Recursive valu
Page 27 and 28: Connecting I/O operations (>>=) ::
Page 29 and 30: Control structures Values of type (
Page 31 and 32: Monads Exceptions type Exn a = E
Page 33 and 34: The IO monad The IO monad allows
Page 35 and 36: What have we achieved? ...without
Page 37 and 38: Open challenge 1 Open problem: the
Page 39 and 40: Monad summary Monads are a beautif
Page 41 and 42: What really matters? Laziness Purit
Page 44 and 45: Type classes class Eq a where (==)
Page 46 and 47: Type classes over time Type classe
Page 48 and 49: Quickcheck propRev :: [Int] -> Bool
Page 50 and 51: Extensiblity Like OOP, one can add
Page 52 and 53: Type-based dispatch class Num a whe
Page 54 and 55: Cool generalisations Multi-paramet
Page 56: Type classes summary A much more f
Page 59 and 60: Is sexy good? Yes! Well typed prog
Page 61 and 62: Destination = F w
Page 63 and 64: Modules Porsche High power, but poo
Page 65 and 66: Encapsulating it all data ST s a --
Page 67 and 68: Shirts off to Wadler Type classes

Wearing the hair shirt Wearing the hair shirt - Microsoft Research

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