HASKELL LANGUAGE REPORT Brett Nelson. John von Neumann.

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1 HASKELL LANGUAGE REPORT Brett Nelson

2 John von Neumann

3 PAUL BERNAYS

4 ALAN TURING

5 ALONZO CHURCH

6 HASKELL CURRY

7 WHAT DO YOU NOTICE?

8 Lambda Calculus Stephen Kleene Alonza Church

9 x.fried-x If we applied chicken to the fryer function like this: x.fried-x chicken => fried-chicken Lambda Fryer Function

10 0 = λf.λx.x 1 = λf.λx.f(x) 2 = λf.λx.f(f(x)) 3 = λf.λx.f(f(f(x))) 4 = λf.λx.f(f(f(f(x)))) Church Integers

11 SUCC = λs.λw.λt.w(s w t) Successor Function

12 SUCC = λs.λw.λt.w(s w t) λs.λw.λt.w(s w t) (λf.λx.x) Successor Function

13 SUCC = λs.λw.λt.w(s w t) λs.λw.λt.w(s w t) (λf.λx.x) λw.λt.w((λf.λx.x) w t) Successor Function

14 SUCC = λs.λw.λt.w(s w t) λs.λw.λt.w(s w t) (λf.λx.x) λw.λt.w((λf.λx.x) w t) w.λt.w((λx.x) t) Successor Function

15 SUCC = λs.λw.λt.w(s w t) λs.λw.λt.w(s w t) (λf.λx.x) λw.λt.w((λf.λx.x) w t) w.λt.w((λx.x) t) λw.λt.w( t ) Successor Function

16 λw.λt.w( t ) 0 = λf.λx.x 1 = λf.λx.f(x) 2 = λf.λx.f(f(x)) 3 = λf.λx.f(f(f(x))) 4 = λf.λx.f(f(f(f(x)))) Church Integers

17 qsort( a, lo, hi ) int a[], hi, lo; { int h, l, p, t; if (lo < hi) { l = lo; h = hi; p = a[hi]; do { while ((l < h) && (a[l] <= p)) l = l+1; while ((h > l) && (a[h] >= p)) h = h-1; if (l < h) { t = a[l]; a[l] = a[h]; a[h] = t; } } while (l < h); t = a[l]; a[l] = a[hi]; a[hi] = t; qsort( a, lo, l-1 ); qsort( a, l+1, hi ); } Quicksort

18 qsort [] = [] qsort (x:xs) = qsort elts_lt_x ++ [x] ++ qsort elts_greq_x where elts_lt_x = [y | y <- xs, y < x] elts_greq_x = [y | y = x] Quicksort

19 Moore’s Law Physical Limits Why Haskell?

20 Bottlenecks

21 If you want to be part of the future of computer science. Learn Haskell and don’t comb your hair. Conclusion