Casting

In mathematics, natural numbers are a strict subset of integers, and can be used in any context where an integer is expected. In LIGO, this property does not hold true in general. Instead, a given binary arithmetic operation, say, is defined four times, so it can apply to any combination of natural numbers and integers: this is called overloading, and some programming languages extend it to user-defined functions (e.g. members in C++) -- but not LIGO.

So there are no implicit type casts in LIGO, but we can explicitly cast natural numbers to integers (this is safe in all contexts where an integer is valid) by calling the predefined function int. The inverse cast, from int to nat is called in mathematics the absolute value, or abs in LIGO.

const one : int = int(1n); // Explicit cast from nat to int

const two : nat = abs(2); // Explicit cast from int to nat