Variadic calls and functions

[p7g]

Variadic calls

New opcode OP_CALL_VARARG expects func and arg array on stack.

New opcode OP_ARRAY_CONCAT has one operand for the number of arrays to concatenate. Pops them off the stack, ensures all are arrays, concatenates, pushes result.

func(a, ...b, c);

OP_LOAD_LOCAL("func")
OP_LOAD_LOCAL("a")
OP_ARRAY_FROM_VALUES(1)
OP_LOAD_LOCAL("b")
OP_LOAD_LOCAL("c")
OP_ARRAY_FROM_VALUES(1)
OP_ARRAY_CONCAT(3)
OP_CALL_VARARG

Variadic functions

Somehow build array holding excess arguments... Can't use OP_ARRAY_FROM_VALUES since length isn't know statically; on the other hand, the bytecode doesn't have access to the actual number of arguments, so it's not possible to use a dynamic version of that opcode. Maybe building the array will have to be part of the call opcode.

[p7g]

The apply and arguments builtins can be used to achieve the same result so this isn't very high priority

[p7g]

Actually arguments doesn't exist so I'll need to add that