A Quick Taste of Haskell (I)

 

 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
we give the flavor of Haskell via examples in the Hugs interactive interpreter
(in the talk itself, we hope to run these examples "live")

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
simple calculation can be done at the interactive prompt 
> 2 + 3 * 5
17

> 37^37
10555134955777783414078330085995832946127396083370199442517

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
Haskell provides exact rational numbers (written with an infix "%") as a safer alternative to floating-point 
> 51 % 3
17 % 1

> (51 % 3) * (2 % 5)
34 % 5

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
bullet Floating-point arithmetic
Traditional IEEE floating-point arithmetic is also available (with the usual caveats) 
> 2.3 ^ 5
64.36343

> $$ * 25.333
1630.51877

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
bullet Floating-point arithmetic
bullet Pairs and tuples
Unlike most languages, Haskell provides pairs and tuples as independent entities (e.g., to return multiple results) 
> 17 `divMod` 3
(5,2)

> 17 `divMod` 3
(5,2)

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
bullet Floating-point arithmetic
bullet Pairs and tuples
bullet Lists of numbers (ellipsis notation)
we can easily generate and manipulate lists of numbers 
> [1..12]
[1,2,3,4,5,6,7,8,9,10,11,12]

> sum [1..10]
55

> product [1..10]
3628800

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
bullet Floating-point arithmetic
bullet Pairs and tuples
bullet Lists of numbers (ellipsis notation)
bullet Z-F expressions
another notational convenience (due to David Turner) is list comprehension, which mimics notation from Zermelo-Fraenkel set theory 
> [ a * b | a<-[1..3], b<-reverse [1..4] ]
[4,3,2,1,8,6,4,2,12,9,6,3]

> [ 2^i | i<-[1..20], odd i]
[2,8,32,128,512,2048,8192,32768,131072,524288]

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 Functional Programming in Haskell
Willamette Mathematics Colloquium • Fall 2002

A Quick Taste of Haskell (I)
bullet An introduction to Haskell through examples
bullet Simple arithmetic, large integers
bullet Exact rational arithmetic
bullet Floating-point arithmetic
bullet Pairs and tuples
bullet Lists of numbers (ellipsis notation)
bullet Z-F expressions
bullet Strings and list operations 
> replicate 3 "hello"
["hello","hello","hello"]

> words "This is a sample text"
["This","is","a","sample","text"]

> unwords (reverse $$)
"text sample a is This"

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