Error not Found value in function param which references other function param

Question

This curried version works fine. Link to Scastie View code in action

def foo(a: Int)(b: Int = a-1): Int = a + b
foo(9)()

But this version throws the Error not found value a. Link to Scastie. View code in action

def bar(a: Int, b: Int = a-1): Int = a+b
bar(9)

Is this an actual error or is there any reason why it is not working?

Parameters are evaluated as they are grouped. The foo works because the 1st group, i.e. the a, is evaluated before the 2nd group, the b. The bar won't compile because a hasn't been evaluated before it is referenced, a-1. — jwvh
– jwvh, Commented Feb 18, 2018 at 4:16

user3097405 · Accepted Answer · 2018-02-18 04:56:59Z

2

Although parameters are evaluated sequentially (and before the body of the function), bar fails because a is not in scope inside its own params list.

The scope of a parameter is only public to the subsequent params list.

def foo(a: Int)(b: Int = a - 1)(c: Int = b + a) = a + b + c 
foo(9)()()
// 34

answered Feb 18, 2018 at 4:56

user3097405

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