[samatman]

For the same reason you can't pass a Python function expecting a list an empty list with foo(), you have to use foo([]). They mean different things.

[int_19h]

However, in Python, if you routinely call foo([]), you'd specify that (or rather an empty tuple since it's immutable) as the default value for that argument.

[owl57]

I believe that if most foo's users should just call it with [], the Pythonic way is to make the argument optional.

[samatman]

Well yes, but if it's someone else's library, realistically you're not going to change it.

Zig is a static language without variadic parameters, so you can't make it optional in that sense. You could make the options a `?T` and pass `null` instead, but it isn't idiomatic, because passing `.{}` to a parameter expecting a `T` will fill in all the default values for you.

[xigoi]

This doesn’t answer the question why Zig doesn’t have default argument values.

[throwawaymaths]

Default argument variables create variadic functions.

Arity N when you supply a value

Arity N-1 when you use the default

[Phil_Latio]

How does this create variadic functions? The arity is the same, since the function signature defines the exact amount of arguments. The compiler just passes the omitted ones for you.

[xigoi]

Okay, but why could a static language not have variadic functions?

[throwawaymaths]

That's their design choice.

I can think of a few reasons

- makes function calling simpler

- faster compilation

- less symbol mangling

- makes grepping for function implementation easier

If for some reason you think you absolutely can't live without variadic functions, maybe don't use zig.