haskell - How is function parameter defined? -

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For this function: 

  plus1 = (+) 1  < / Ex> 
 I can use it: 
 
  prelude & gt; Plus 1 3 4  
 
 Plus 1 type 
 
  plus1 :: integer - & gt; Integer  
 
 How is the function parameter integer being allowed here? In my function definition where the integer function parameter is defined? 
 
 I'm not sure what to expect from me but all the parameters coming from Java need to be defined as part of the law, but does it feel like going behind the scenes here Used to be?

(if we ignore the num typeclass for a second and The excuse that only works on integer s to work), (+) is a type of function -> (Integer -> integer) (parentheses are not required because -> is correct, but I've added them for clarity). This means that the argument of integer type and one type of type does ->

So when you apply (+) to the integer 1 , you actually get one of its functions as the result type Since the add1 holds, it is a type of task integer - & gt; Integer and this is the reason that you can apply it as the plus1 3 .


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