[Haskell-beginners] A neat, simple example of making code more efficient

[Matthias Guedemann]

Hi Roger,

> Which is itself a square operation:
> 
>     square (square a)

this is a special case of square-and-multiply or binary exponentiation
(see http://en.wikipedia.org/wiki/Exponentiation_by_squaring)

general square and multiply also works for an odd exponent and reduces
the complexity from O(n) to O(log n)

regards
Matthias