Introduction to functional programming and Haskell

 

 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
Mainstream languages are imperative or object-oriented; functional programs are more like mathematical expressions, i.e., without side-effects

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
In traditional languages, even the simplest aspects of algebraic and equational reasoning can fail 
f(x) + f(x) == 2 * f(x)

g(y) == g(y)

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
bullet A high-level perspective on programming
Powerful abstraction features (higher-order functions, polymorphic types, etc.) allow for very concise expression of programs and a high "signal-to-noise" ratio 
quicksort [] = []
quicksort (x:xs) = quicksort small ++ [x] ++ quicksort large
                   where small = [y | y<-xs, y< x]
                         large = [y | y<-xs, y>=x]

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
bullet A high-level perspective on programming
bullet Haskell and other functional programming languages
Most functional languages (LISP, APL, Scheme, ML) make concessions to side-effects; Haskell is a study in pure functional style (plus, it uses a familiar algebraic syntax)

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
bullet A high-level perspective on programming
bullet Haskell and other functional programming languages
bullet Regional relevance in the Northwest
  • the OGI Pacsoft group is a world leader in Haskell and FP
  • Intel uses Haskell and other FPs for hardware modeling and development
  • Galois Connections: a profitable private company with industrial and government contracts
  • Microsoft has bought into Haskell, both in Cambridge and Redmond

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
bullet A high-level perspective on programming
bullet Haskell and other functional programming languages
bullet Regional relevance in the Northwest
bullet Overview of the tutorial
  • basic syntax and features of Haskell (by example)
  • short applications (text processing, number bases, DFA simulation, etc.)
  • medium-sized example: generic sorting and simple database
  • medium-sized example: parsing and evaluating a simple expression language
  • medium-sized example: simple vector graphics package
  • overview of larger applications and libraries (music, graphics, animation, GUIs, web, etc.)

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 Functional Programming in Haskell
3rd CCSC Northwest Conference • Fall 2001

Introduction to functional programming and Haskell
bullet Functional languages: an alternative paradigm
bullet Lack of side-effects facilitates logical reasoning and formal methods
bullet A high-level perspective on programming
bullet Haskell and other functional programming languages
bullet Regional relevance in the Northwest
bullet Overview of the tutorial
bullet Haskell tools and resources (see also the physical hand-out)

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