Wearing the hair shirt Wearing the hair shirt - Microsoft Research
Wearing the hair shirt Wearing the hair shirt - Microsoft Research Wearing the hair shirt Wearing the hair shirt - Microsoft Research
“Expression style” Define a function as an expression map = \f xs -> case xs of [] -> [] (x:xs) -> map f xs sign = \x -> if x>0 then 1 else if x==0 then 0 else -1
Fat vs thin Expression style •Let •Lambda •Case •If Declaration style •Where •Function arguments on lhs •Pattern-matching •Guards SLPJ’s conclusion syntactic redundancy is a big win Tony Hoare’s comment “I fear that Haskell is doomed to succeed”
- 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 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 25 and 26: Monadic I/O A value of type (IO t)
- 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
“Expression style”<br />
Define a function as an expression<br />
map = \f xs -> case xs of<br />
[] -> []<br />
(x:xs) -> map f xs<br />
sign = \x -> if x>0 <strong>the</strong>n 1<br />
else if x==0 <strong>the</strong>n 0<br />
else -1
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