Modular•13mo ago

Compile time addition of numbers

I am trying to do compile time addition of numbers via generic types, e.g.

from memory import stack_allocation

struct IntType[num: Int]:
   alias value: Int = num

fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
   return Num1.value + Num2.value

from memory import stack_allocation

struct IntType[num: Int]:
   alias value: Int = num

fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
   return Num1.value + Num2.value

The errors are:

array2.mojo:6:31: error: use of unknown declaration 'num1'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                              ^~~~
array2.mojo:6:57: error: use of unknown declaration 'num2'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                                                        ^~~~
array2.mojo:6:82: error: use of unknown declaration 'num1'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                                                                                 ^~~~
array2.mojo:6:89: error: use of unknown declaration 'num2'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:

array2.mojo:6:31: error: use of unknown declaration 'num1'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                              ^~~~
array2.mojo:6:57: error: use of unknown declaration 'num2'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                                                        ^~~~
array2.mojo:6:82: error: use of unknown declaration 'num1'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:
                                                                                 ^~~~
array2.mojo:6:89: error: use of unknown declaration 'num2'
fn comptime_add[Num1: IntType[num1: Int], Num2: IntType[num2: Int]]() -> IntType[num1 + num2]:

How should I approach this?

1 Reply

Stole•13mo ago

You can directly use Int, no need for IntType

fn comptime_add[Num1: Int, Num2: Int]() -> Int:
   return Num1 + Num2

fn main():
    alias N = comptime_add[1, 2]()
    print(N)

fn comptime_add[Num1: Int, Num2: Int]() -> Int:
   return Num1 + Num2

fn main():
    alias N = comptime_add[1, 2]()
    print(N)

This prints 3 as expected

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Compile time addition of numbers