Question

countSequences :: Int -> Int -> Integer

countSequences 0 m = 0
countSequences m 0 = 0
countSequences (n) (m) =  if (n <= (m+1)) then (truncate((cee (m+1) (n) (0))) + truncate((countSequences (fromIntegral (n-1)) (fromIntegral (m))))) 
else truncate(countSequences (fromIntegral (n-1)) (fromIntegral (m)))

factorial :: Float -> Float
factorial 0 = 1
factorial 1 = 1
factorial x = x * factorial(x-1)

cee :: Float -> Float -> Float -> Float

cee x y z = if (x==y) then ((1) / (factorial ((x+z)-(y)))) else ((x) * (cee (x-1) (y) (z+1)))

i cant really understand why this error keep coming up .. the truncate is supposed to convert the type from Float to Integer so ..

Answer 1

m is of type Int (per your type signature for countSequences: hence, so is m + 1. However, your function cee expects a Float, so the type checker righteously complains.

Furthermore, you will need a couple of more fixes to make this type check. Here’s a version that passes the checker:

countSequences :: Int -> Int -> Integer
countSequences 0 m = 0
countSequences m 0 = 0
countSequences n m =
  if   n <=  m + 1
  then truncate $
         cee (fromIntegral (m+1)) (fromIntegral n) 0 +
         fromIntegral (countSequences (n-1) m)
  else countSequences (n-1) m