codon/docs/language/extra.md

Codon supports a number of additional types that are not present in plain Python.

Arbitrary-width integers

Codon's int type is a 64-bit signed integer. However, Codon supports arbitrary-width signed and unsigned integers:

a = Int[16](42)    # signed 16-bit integer 42
b = UInt[128](99)  # unsigned 128-bit integer 99

The Codon standard library provides shorthands for the common variants:

• i8/u8: signed/unsigned 8-bit integer
• i16/u16: signed/unsigned 16-bit integer
• i32/u32: signed/unsigned 32-bit integer
• i64/u64: signed/unsigned 64-bit integer

Pointers

Codon has a Ptr[T] type that represents a pointer to an object of type T. Pointers can be useful when interfacing with C. The __ptr__ keyword can also be used to obtain a pointer to a variable:

p = Ptr[int](100)  # allocate a buffer of 100 ints
p = Ptr[int]()     # null pointer

x = 42
p = __ptr__(x)     # pointer to x, like "&x" in C

from C import foo(Ptr[int])
foo(p)             # pass pointer to C function

The cobj alias corresponds to void* in C and represents a generic C or C++ object.

{% hint style="warning" %} Using pointers directly circumvents any runtime checks, so dereferencing a null pointer, for example, will cause a segmentation fault just like in C. {% endhint %}

Static arrays

The __array__ keyword can be used to allocate static arrays on the stack:

def foo(n):
    arr = __array__[int](5)  # similar to "long arr[5]" in C
    arr[0] = 11
    arr[1] = arr[0] + 1
    ...