# [Haskell-cafe] Define variable types

Tsunkiet Man temp.tsun at gmail.com
Thu Feb 5 06:37:22 EST 2009

```Hello,

I'm new to Haskell and it seems like a very nice language to learn. However
I'm not really familiar with the errormessages it produces. I am using a
Helium interpreter. I've created the following module (however it is just a
small sketch). I've written the following code:

fac :: Int -> Int
fac n = product[1..n]

boven :: Int -> Int -> Int
boven n k = (fac n) `div` fac k * fac (n-k)

bin :: Int -> Int -> Int -> Int
bin n k p   |(n-k)>0 && k>0 = (boven n k) * (p^k) * (1-p)^(n-k)
|(n-k)<0 && k>0 = (boven n k) * (p^k) * (1/((1-p)^(-(n-k))))
|(n-k)<0 && k<0 = (boven n k) * (1/(p^(-k))) *
(1/((1-p)^(-(n-k))))

When I load this into my interpreter it says:

Compiling ./Test.hs
(11,55): Type error in infix application
expression       : 1 / ((1 - p) ^ (-(n - k)))
operator         : /
type           : Float -> Float -> Float
does not match : Int   -> Int   -> Int
(12,47): Type error in infix application
expression       : 1 / (p ^ (-k))
operator         : /
type           : Float -> Float -> Float
does not match : Int   -> Int   -> a
(12,62): Type error in infix application
expression       : 1 / ((1 - p) ^ (-(n - k)))
operator         : /
type           : Float -> Float -> Float
does not match : Int   -> Int   -> a
Compilation failed with 3 errors

Some details that might be usefull:

Line 11 is |(n-k)<0 && k>0 = (boven n k) * (p^k) * (1/((1-p)^(-(n-k))))
Line 12 is |(n-k)<0 && k<0 = (boven n k) * (1/(p^(-k))) *
(1/((1-p)^(-(n-k))))

So my question is: how can I fix these errors?

(I used these lines of codes because it is not possible to use a negative
exponent in the Helium interpreter.)

Thank you for answering my question!

Greetings JTKM
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20090205/d7ab59f9/attachment.htm
```

More information about the Haskell-Cafe mailing list