[Haskell-cafe] Roman to Decimal Algorithms

Andrew Savige ajsavige at yahoo.com.au
Sun Jun 7 18:47:23 EDT 2009

Martijn van Steenbergen wrote:
> Why not rename mod like so?
> (%)=mod
> rtoa c=10^(205558%ord c%7)%9995

Thanks Martijn. My first Haskell golfing tip. :)

I found I had to write it with an extra set of parens to get it to work:

rtoa c=(10^(205558%ord c)%7)%9995

Though it wasn't my original intention to play Haskell golf, assuming
upper case Roman Numerals, we can now write the whole thing as:

romanToInt=foldl1(\t n->t+n-t%n*2).map(\c->(10^(205558%ord c)%7)%9995)

Can anyone shorten that further?


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