Transcript

1. Functional Programming Ionut G. Stan - OpenAgile 2010

2. Functional Programming what why how

3. Functional Programming what why how

4. What is FP a programming style

9. Imperative Programming programming: telling a computer what to do

13. von Neumann architecture

19. What is FP a programming style conceptually derived from lambda

    calculus (1930s) not procedural programming functions as in mathematical functions trying to plug the abstraction leak tell the computer what to do, not how mutations not allowed (no variables, just identifiers) no statements, just expressions (if/then/else is expression)

20. What is FP a programming style conceptually derived from lambda

    calculus (1930s) not procedural programming functions as in mathematical functions trying to plug the abstraction leak tell the computer what to do, not how mutations not allowed (no variables, just identifiers) no statements, just expressions (if/then/else is expression) functions are deterministic and side-effect free

21. What is FP a programming style conceptually derived from lambda

    calculus (1930s) not procedural programming functions as in mathematical functions trying to plug the abstraction leak tell the computer what to do, not how mutations not allowed (no variables, just identifiers) no statements, just expressions (if/then/else is expression) functions are deterministic and side-effect free functions are all we need to model computation

22. What is FP a programming style conceptually derived from lambda

    calculus (1930s) not procedural programming functions as in mathematical functions trying to plug the abstraction leak tell the computer what to do, not how mutations not allowed (no variables, just identifiers) no statements, just expressions (if/then/else is expression) functions are deterministic and side-effect free functions are all we need to model computation execution order is not guaranteed

23. Functional Programming what why how

24. Why FP easier to reason about programs

25. Why FP easier to reason about programs heisenbugs

26. Why FP easier to reason about programs heisenbugs race conditions

29. Why FP easier to reason about programs

30. Why FP easier to reason about programs easier to parallelize

35. Functional Programming what why how

36. Functional Programming what why how (even in imperative languages)

37. How to FP avoid side-effects/mutation as much as possible

42. Functional Programming what why how example

43. Example

44. Example

45. Example

46. "Conventional programming languages are growing ever more enormous, but not

    stronger. Inherent defects at the most basic level cause them to be both fat and weak: their primitive word- at-a-time style of programming inherited from their common ancestor -- the von Neumann computer, their close coupling of semantics to state transitions, their division of programming into a world of expressions and a world of statements, their inability to effectively use powerful combining forms for building new programs from existing ones, and their lack of useful mathematical properties for reasoning about programs." John Backus, known for Fortran, Algol and BNF

47. Thank You igstan.ro | [email protected] | @igstan

48. Questions? igstan.ro | [email protected] | @igstan