The definition of fac forces the result to have the same type as the
argument.
Then in binom you use / which forces the type to be Fractional.
And finally you use ^ which forces the type to be Integral.
There is no type that is both Fractional and Integral.
I suggest using div instead of / in binom (binomial coefficients are
integers after all).
And then a fromIntegral applied to the binom call in bernoulli.
-- Lennart
On Mar 31, 2007, at 10:04 , Scott Brown wrote:
I have written this code in Haskell which gives an unresolved
overloading error.
The function bernoulli should give the probability of j successes
occuring in n trials, if each trial has a probability of p.
> fac 0 = 1
> fac n = n * fac(n - 1)
> binom n j = (fac n)/((fac j)*(fac (n - j)))
> bernoulli n p j = (binom n j)*(p ^ j) * ((1 - p)^(n - j))
However, bernoulli 6 0.5 3 gives the error:
ERROR - Unresolved overloading
*** Type : (Fractional a, Integral a) => a
*** Expression : bernoulli 6 0.5 3
Why doesn't Haskell infer the types? What kind of type casting or
type definition can I use to fix the error?
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