[Haskell-beginners] help with lists and tuples

[Alexander O'Neill]

It seems like you want to set up a recursive function. So you want to take one tuple out of the list of tuples, perform your sum function on it, and then call the recursive function on the remainder of the list.  Something like this, maybe?

nActivationSum :: [(Float, Float)] -> [Float]
nActivationSum [] = []
nActivationSum ((input,weight) : rest) = nActivation (input, weight) : nActivat\
ionSum rest


On 2013-04-14, at 4:04 PM, Miro Karpis <miroslav.karpis at gmail.com> wrote:

> Please can you help me with this? What I want is to have on input a list of tuple (size 2) and on output list of floats. So now I'm returning only float instead of a list. But unfortunately I can't figure out how to implement the list......
> 
> 
> sigmoid :: Float -> Float
> sigmoid x = 1.0 / (1 + exp (-x))
> 
> nActivation :: (Float,Float) -> Float
> nActivation (x,y) = sigmoid(x*y) 
> 
> nActivationSum :: [(Float, Float)] -> [Float]
> nActivationSum [] = []
> nActivationSum (inputs:weights) = nActivation (inputs, weights)
> 
> 
> 
> Couldn't match expected type `[Float]' with actual type `Float'
>     In the return type of a call of `nActivation'
>     In the expression: nActivation (inputs, weights)
>     In an equation for `nActivationSum':
>         nActivationSum (inputs : weights) = nActivation (inputs, weights)
> 
> 
> thanks,
> m.
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