* [const is a
contract](https://quuxplusone.github.io/blog/2019/01/03/const-is-a-contract/).
I like to see that Nim could generate something similar to `f(O *a, const O
*b)` for below f:
type
O {.byref.} = object ...
proc f*(a: var O; b: O): int = ...
Run
* const is not only a contract, seriously
We need a const/immutable `ptr T` to help us from crash, not just reading and
remembering the signature of the C function:
{.emit: """
const int a = 1234;
const int *fconst(void) { return &a; }
"""
.}
proc myf(): ptr int {.importc: "fconst" nodecl.}
proc f(): int =
let p = myf()
p[] = 456
return p[]
Run
P.S. C can't do **X** is not reason for Nim not to do **Y**.
