Small things...

Good grief... I've let this go for a month. (UPDATE: No, I haven't. It helps to read the dates carefully.)

An option in pattern matching that I wasn't fully aware of: you can use _ when you don't care about what is there, and have no need to refer to it. I guess I did use it on the ByteString readInteger that returns Maybe(Integer, ByteString):

process line = case map B.readInteger (B.words line) of
               [Just (m, _), Just (n, _)] -> numXs m n
               _                          -> -1

But I didn't realize that I could use it in

ysInRange m n d
    | nVal == n = nPos - mPos + 1
    | otherwise = nPos - mPos
    where (_,    mPos) = findFirst' m
          (nVal, nPos) = findFirst' n
          findFirst' x = case findFirst (Ge x, Any) (dDigitYTree d) of
                             Just (Max i, Max j) -> (i, j)
                             Nothing             -> (tenToThe d, numNDigitYs d)

because we need only check for an exact match at the high end.


Popular posts from this blog

Haskell Tool Stack for Ubuntu 16.04

TMTOWTDI, Haskell Style

Fun with pattern matching