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Property Based Dispatch in Functional Languages Property Based Dispatch in Functional Introduction Olena Properties Languages Lisp Implementation Other Languages Christopher Chedeau Conclusion LRDE Laboratoire de Recherche et D

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Property Based Dispatch in Functional Languages

Christopher Chedeau

LRDE Laboratoire de Recherche et D´ eveloppement d’EPITA

January 18, 2012 http://lrde.epita.fr/

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Olena Properties

Type Name Values image dimension any, one d, two d, three d

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Shift Algorithm

definition any unique multiple varying Specialization (1)

Specialization (2)
size

any fixed Specialization (1)

Specialization (2)
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Christopher Chedeau

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

C++ Implementation

shift(Window<W>& win, mln dpsite(W)& dp) { // Dispatch on definition property shift (mln trait window definition(W)(), exact(win), dp); } shift (trait::window::definition::unique, W& win, mln dpsite(W)& dp) { /✯ Specialized implementation (1) ✯/ } shift (trait::window::definition::multiple, W& win, mln dpsite(W)& dp) { /✯ Specialized implementation (2) ✯/ }

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Shift Algorithm

definition any unique multiple varying Specialization (1) Ö

Ö Specialization (2) Ö Ö

size any fixed Specialization (1) Ö

Specialization (2)
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Christopher Chedeau

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

C++ Implementation

shift(Window<W>& win, mln dpsite(W)& dp) { mlc is not(mln trait window definition(W), trait::window::definition::any)::check(); mlc is not(mln trait window definition(W), trait::window::definition::varying)::check(); shift (mln trait window definition(W)(), exact(win), dp); } shift (trait::window::definition::unique, W& win, mln dpsite(W)& dp) { mlc is(mln trait window size(W), trait::window::size::fixed)::check(); }

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Lisp Implementation

(defmethod shift ( (win window) (dp dpsite)) ; Specialization (1) ) (defmethod shift ( (win window) (dp dpsite)) ; Specialization (2) )

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Lisp Implementation

(defalgo shift ( (win :properties ( :definition :unique :size :fixed) window) (dp dpsite)) ; Specialization (1) ) (defalgo shift ( (win :properties ( :definition :multiple) window) (dp dpsite)) ; Specialization (2) )

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Implementation Overview

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Christopher Chedeau

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Fibonacci

(defalgo fibo ((n (lambda (n) (< n 2)))) n)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Fibonacci

(defalgo fibo ((n (lambda (n) (< n 2)))) n) (defun <2 (n) (< n 2)) (defalgo fibo ((n #’<2)) n)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Fibonacci

(defalgo fibo ((n (lambda (n) (< n 2)))) n) (defun <2 (n) (< n 2)) (defalgo fibo ((n #’<2)) n) (defun is (a) (lambda (b) (eq a b))) (defalgo fibo ((n (is 0))) 0) (defalgo fibo ((n (is 1))) 1)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Fibonacci

(defalgo fibo ((n (lambda (n) (< n 2)))) n) (defun <2 (n) (< n 2)) (defalgo fibo ((n #’<2)) n) (defun is (a) (lambda (b) (eq a b))) (defalgo fibo ((n (is 0))) 0) (defalgo fibo ((n (is 1))) 1) (defalgo fibo (n) (+ (fibo (− n 2)) (fibo (− n 1))))

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Javascript Full Dispatch

fibo = FullDispatch() fibo.add [(n) −> n < 2], (n) −> n fibo.add [null], (n) −> fibo(n − 1) + fibo(n − 2)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Python Decorators

@dispatch(inside(0, 1)) def fibo(n): return n @dispatch(int) def fibo(n): return fibo(n − 1) + fibo(n − 2)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Haskell Pattern Matching

fibo 0 = 0 fibo 1 = 1 fibo n = fibo (n − 1) + fibo (n − 2)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

MOP

(defmethod fibo (n) (+ (fibo (− n 1)) (fibo (− n 2)))) (defmethod fibo ((n (eql 1))) n) (defmethod fibo ((n (eql 0))) n)

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Filtered Dispatch

(defun state (n) (if (< n 2) ’terminal ’general)) (defmethod fibo :filter :state ((n (eql ’terminal))) n) (defmethod factorial :filter :state ((n (eql ’general))) (+ (fibo (− n 1)) (fibo (− n 2))))

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Multimethod.js

fibo = multimethod() .dispatch((n) −> if n < 2 ’terminal’ else ’general’) .when(’terminal’, (n) −> n) .when(’general’, (n) −> fibo(n − 1) + fibo(n − 2))

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Conclusion

◮ Conclusion 18 / 19 Christopher Chedeau

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Property Based Dispatch in Functional Languages

Introduction Olena Properties Lisp Implementation Other Languages Conclusion

Questions ?

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