[Haskell-cafe] expension of fractions

Tom Pledger tom at pledger.gen.nz
Wed Jul 25 22:55:38 EDT 2007

```Arie Groeneveld wrote:
:
| Looking at the result of my rewriting gives me the idea it isn't
| Haskelly enough.
|
| Anyways, here's my interpretation:
|
| -- period m/n base = (period length, preperiod digits, period digits)
| period :: Integer -> Integer -> Integer -> (Int, ([Integer], [Integer]))
:

Haskelliness

I'd be inclined to try using a Rational (from Data.Ratio) and the
properFraction function, instead of numerators and denominators and gcd.

You could do away with the parts where you subscript a linked list, if
you did something with elem and zip and span instead of findIndex and
splitAt.

Instead of translating Nothing to -1 and Just i to i, you could use
the result of findIndex directly in a case expression.

Correctness

*Main> period 8 70 10
(6,([0],[5,7,1,4,2,8]))

That should be (6,([1],[1,4,2,8,5,7])).

Regards,
Tom

```

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