[Haskell-cafe] OOP'er with (hopefully) trivial questions.....

Ketil Malde ketil+haskell at ii.uib.no
Mon Dec 17 06:10:04 EST 2007

"Nicholls, Mark" <Nicholls.Mark at mtvne.com> writes:

> After many years of OOP though my brain is wired up to construct software in
> that ?pattern??.a problem for me at the moment is I cannot see how to construct
> programs in an OO style in Haskell?.I know this is probably not the way to
> approach it?but I feel I need to master the syntax before the paradigm.

Mostly, you'd use an algebraic data type.  I.e.

  data Shape = Square Int | Rectangle Int Int | Circle Int

  area :: Shape -> Int
  area (Square x)      = x^2
  area (Rectangle x y) = x * y
  area (Circle r)      = pi*r^2

If I haven't seen further, it is by standing in the footprints of giants

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