rand: simplify rand.PRNG, move to optional types for error handling (#13570)

vlib/rand/splitmix64/splitmix64.v

@@ -50,180 +50,6 @@ pub fn (mut rng SplitMix64RNG) u64() u64 {
 	return z ^ (z >> (31))
 }
 
-// u32n returns a pseudorandom `u32` less than `bound`.
-[inline]
-pub fn (mut rng SplitMix64RNG) u32n(bound u32) u32 {
-	// This function is kept similar to the u64 version
-	if bound == 0 {
-		eprintln('max must be non-zero')
-		exit(1)
-	}
-	threshold := -bound % bound
-	for {
-		r := rng.u32()
-		if r >= threshold {
-			return r % bound
-		}
-	}
-	return u32(0)
-}
-
-// u64n returns a pseudorandom `u64` less than `bound`.
-[inline]
-pub fn (mut rng SplitMix64RNG) u64n(bound u64) u64 {
-	// See pcg32.v for explanation of comment. This algorithm
-	// existed before the refactoring.
-	if bound == 0 {
-		eprintln('max must be non-zero')
-		exit(1)
-	}
-	threshold := -bound % bound
-	for {
-		r := rng.u64()
-		if r >= threshold {
-			return r % bound
-		}
-	}
-	return u64(0)
-}
-
-// u32n returns a pseudorandom `u32` value that is guaranteed to be in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) u32_in_range(min u32, max u32) u32 {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	return min + rng.u32n(max - min)
-}
-
-// u64n returns a pseudorandom `u64` value that is guaranteed to be in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) u64_in_range(min u64, max u64) u64 {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	return min + rng.u64n(max - min)
-}
-
-// int returns a pseudorandom 32-bit (possibly negative) `int`.
-[inline]
-pub fn (mut rng SplitMix64RNG) int() int {
-	return int(rng.u32())
-}
-
-// i64 returns a pseudorandom 64-bit (possibly negative) `i64`.
-[inline]
-pub fn (mut rng SplitMix64RNG) i64() i64 {
-	return i64(rng.u64())
-}
-
-// int31 returns a positive pseudorandom 31-bit `int`.
-[inline]
-pub fn (mut rng SplitMix64RNG) int31() int {
-	return int(rng.u32() & constants.u31_mask) // Set the 32nd bit to 0.
-}
-
-// int63 returns a positive pseudorandom 63-bit `i64`.
-[inline]
-pub fn (mut rng SplitMix64RNG) int63() i64 {
-	return i64(rng.u64() & constants.u63_mask) // Set the 64th bit to 0.
-}
-
-// intn returns a pseudorandom `int` in range `[0, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) intn(max int) int {
-	if max <= 0 {
-		eprintln('max has to be positive.')
-		exit(1)
-	}
-	return int(rng.u32n(u32(max)))
-}
-
-// i64n returns a pseudorandom `i64` in range `[0, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) i64n(max i64) i64 {
-	if max <= 0 {
-		eprintln('max has to be positive.')
-		exit(1)
-	}
-	return i64(rng.u64n(u64(max)))
-}
-
-// int_in_range returns a pseudorandom `int` in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) int_in_range(min int, max int) int {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	// This supports negative ranges like [-10, -5) because the difference is positive
-	return min + rng.intn(max - min)
-}
-
-// i64_in_range returns a pseudorandom `i64` in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) i64_in_range(min i64, max i64) i64 {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	return min + rng.i64n(max - min)
-}
-
-// f32 returns a pseudorandom `f32` value in range `[0, 1)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f32() f32 {
-	return f32(rng.u32()) / constants.max_u32_as_f32
-}
-
-// f64 returns a pseudorandom `f64` value in range `[0, 1)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f64() f64 {
-	return f64(rng.u64()) / constants.max_u64_as_f64
-}
-
-// f32n returns a pseudorandom `f32` value in range `[0, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f32n(max f32) f32 {
-	if max <= 0 {
-		eprintln('max has to be positive.')
-		exit(1)
-	}
-	return rng.f32() * max
-}
-
-// f64n returns a pseudorandom `f64` value in range `[0, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f64n(max f64) f64 {
-	if max <= 0 {
-		eprintln('max has to be positive.')
-		exit(1)
-	}
-	return rng.f64() * max
-}
-
-// f32_in_range returns a pseudorandom `f32` in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f32_in_range(min f32, max f32) f32 {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	return min + rng.f32n(max - min)
-}
-
-// i64_in_range returns a pseudorandom `i64` in range `[min, max)`.
-[inline]
-pub fn (mut rng SplitMix64RNG) f64_in_range(min f64, max f64) f64 {
-	if max <= min {
-		eprintln('max must be greater than min')
-		exit(1)
-	}
-	return min + rng.f64n(max - min)
-}
-
 // free should be called when the generator is no longer needed
 [unsafe]
 pub fn (mut rng SplitMix64RNG) free() {