rand: move the shuffle function from arrays to rand.util (#8587)

vlib/arrays/arrays.v

@@ -3,9 +3,7 @@ module arrays
 // Common arrays functions:
 // - min / max - return the value of the minumum / maximum
 // - idx_min / idx_max - return the index of the first minumum / maximum
-// - shuffle - randomize array items order in place (allowing exit after n items)
 // - merge - combine two sorted arrays and maintain sorted order
-import rand
 
 // min returns the minimum
 [direct_array_access]
@@ -71,22 +69,6 @@ pub fn idx_max<T>(a []T) int {
 	return idx
 }
 
-// shuffle randomizes the first n items of an array in place (all if n=0)
-[direct_array_access]
-pub fn shuffle<T>(mut a []T, n int) {
-	if n < 0 || n > a.len {
-		panic("shuffle's argument 'n' must be in range [0,a.len]")
-	}
-	cnt := if n == 0 { a.len - 1 } else { n }
-	for i in 0 .. cnt {
-		x := rand.int_in_range(i, a.len)
-		// swap
-		a_i := a[i]
-		a[i] = a[x]
-		a[x] = a_i
-	}
-}
-
 // merge two sorted arrays (ascending) and maintain sorted order
 [direct_array_access]
 pub fn merge<T>(a []T, b []T) []T {
@@ -119,3 +101,8 @@ pub fn merge<T>(a []T, b []T) []T {
 	}
 	return m
 }
+
+[deprecated]
+pub fn shuffle<T>(mut a []T, n int) {
+	panic('Please use rand.util.shuffle() instead')
+}

vlib/arrays/arrays_test.v

@@ -44,31 +44,6 @@ fn test_idx_max() {
 	assert idx_max<byte>(c) == 1
 }
 
-fn test_shuffle() {
-	rand.seed([u32(1), 2]) // set seed to produce same results in order
-	a := [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-	mut b := a.clone()
-	mut c := a.clone()
-	shuffle<int>(mut b, 0)
-	shuffle<int>(mut c, 0)
-	assert b == [6, 4, 5, 1, 9, 2, 10, 3, 8, 7]
-	assert c == [1, 6, 5, 8, 7, 2, 10, 9, 3, 4]
-	// test shuffling a slice
-	mut d := a.clone()
-	shuffle<int>(mut d[..5], 0)
-	assert d == [5, 2, 1, 3, 4, 6, 7, 8, 9, 10]
-	assert d[5..] == a[5..]
-	// test shuffling n items
-	mut e := a.clone()
-	shuffle<int>(mut e, 5)
-	assert e[..5] == [10, 3, 1, 8, 4]
-	assert e[5..] == [6, 7, 5, 9, 2]
-	// test shuffling empty array
-	mut f := a[..0]
-	shuffle<int>(mut f, 0)
-	assert f == []int{}
-}
-
 fn test_merge() {
 	a := [1, 3, 5, 5, 7]
 	b := [2, 4, 4, 5, 6, 8]