16 lines
541 B
Text
16 lines
541 B
Text
open number string math
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digit x y z k =
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[[x],[x,x],[x,x,x],[x,y],[y],[y,x],[y,x,x],[y,x,x,x],[x,z]] :
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(toInt k - 1)
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toRoman 0 = ""
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toRoman x | x < 0 = fail "Negative roman numeral"
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| x >= 1000 = 'M' :: toRoman (x - 1000)
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| x >= 100 = let (q,r) = x `divrem` 100 in
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digit 'C' 'D' 'M' q ++ toRoman r
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| x >= 10 = let (q,r) = x `divrem` 10 in
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digit 'X' 'L' 'C' q ++ toRoman r
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| else = digit 'I' 'V' 'X' x
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map (join "" << toRoman) [1999,25,944]
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