1 files changed, 30 insertions, 0 deletions

diff --git a/Data/BaseConvert.hs b/Data/BaseConvert.hs
new file mode 100644
index 0000000..655f593
--- /dev/null
+++ b/Data/BaseConvert.hs
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+module Data.BaseConvert (toString, toNum, toAlphaDigit, fromAlphaDigit) where
+
+import Data.Sequence
+import Data.Foldable (toList)
+import Data.List
+import Data.Char
+
+digit_alphabet :: [Char]
+digit_alphabet = ['0'..'9'] ++ ['A'..]
+
+toBase :: (Integral a) => a -> a -> [a]
+toBase _ 0 = [0]
+toBase b v = toList $
+        unfoldl (\n -> if n == 0 then Nothing else Just (n `divMod` b)) v
+
+toAlphaDigit :: (Integral a) => a -> Char
+toAlphaDigit = (digit_alphabet !!) . fromIntegral
+
+toString :: (Integral a) => a -> a -> String
+toString b v = map toAlphaDigit (toBase b v)
+
+fromAlphaDigit :: (Num a) => Char -> a
+fromAlphaDigit v = fromIntegral n
+        where Just n = elemIndex (toUpper v) digit_alphabet
+
+fromBase :: (Num a) => a -> [a] -> a
+fromBase b = foldl (\n k -> n * b + k) 0
+
+toNum :: (Num a) => a -> String -> a
+toNum b v = fromBase b (map fromAlphaDigit v)