CODEWITHSUNDEEP
haskellghci
user1786327
user1786327

Reputation: 43

Parse Error on input 'sum' in haskell

I'm writing a short program in haskell to find the mean of the list of odd numbers between 1 and 2000 that are not divisible by 3 or 5. I can't get it to compile and keep getting a variety of errors. I made some changes and now the code is giving me a "Parse error on input 'sum'" on line 5 col 9. Could someone tell me what I'm doing wrong please?

--Write a Haskell function that calculates the mean of a list of odd numbers that
--are not divisible by 3 or 5 and whose sum is less than 2000.
mean :: Int
mean = let nums = [x|x <- [1,3..1999], x 'mod' 3 != 0, x 'mod' 5 != 0]
    sum nums/length nums

I'm compiling with GHCI. Thanks

Upvotes: 1

Views: 664

Answers (2)

Jan Christiansen
Jan Christiansen

Reputation: 3173

Besides the missing in as mentioned by DiegoNolan there are some other minor problems with your definition. First, to use a two-ary function infix, you have to enclose it in backticks ` while you use ticks '. Furthermore, Haskell uses /= for inequality and not !=. Finally, you cannot use / for integer division but function div.

mean = let nums = [x|x <- [1,3..1999], x `mod` 3 /= 0, x `mod` 5 /= 0]
       in
       sum nums `div` length nums

Upvotes: 4

DiegoNolan
DiegoNolan

Reputation: 3766

you need in

mean :: Int
mean = let nums = [x|x <- [1,3..1999], x 'mod' 3 != 0, x 'mod' 5 != 0]
       in sum nums/length nums

Upvotes: 2

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