math.nula

// Nulang standard library — math functions.
// Language version: 2.0.0-alpha

/// Absolute value.
pub fn abs(x: Int) -> Int {
    if x < 0 then -x else x
}

/// Minimum of two integers.
pub fn min(a: Int, b: Int) -> Int {
    if a < b then a else b
}

/// Maximum of two integers.
pub fn max(a: Int, b: Int) -> Int {
    if a > b then a else b
}

/// Clamp x to the range [lo, hi].
pub fn clamp(x: Int, lo: Int, hi: Int) -> Int {
    if x < lo then lo
    else if x > hi then hi
    else x
}

/// Integer exponentiation (x^y) for non-negative y.
pub fn pow(base: Int, exp: Int) -> Int {
    let rec loop(b: Int, e: Int, acc: Int) -> Int {
        if e == 0 then acc
        else loop(b, e - 1, acc * b)
    }
    in loop(base, exp, 1)
}

/// Factorial. Returns 1 for n <= 1.
pub fn factorial(n: Int) -> Int {
    let rec loop(i: Int, acc: Int) -> Int {
        if i <= 1 then acc
        else loop(i - 1, acc * i)
    }
    in loop(n, 1)
}

/// Greatest common divisor (Euclidean algorithm).
pub fn gcd(a: Int, b: Int) -> Int {
    if b == 0 then abs(a)
    else gcd(b, a % b)
}