From de9200e9f8e78853c5f86b17a37776fe9239d314 Mon Sep 17 00:00:00 2001
From: Bob Glickstein <bobg@emphatic.com>
Date: Sun, 13 Aug 2023 11:37:37 -0700
Subject: [PATCH 1/4] Adapt to changes in exp/slices.

---
 go.mod                |   2 +-
 go.sum                |   2 +
 slices/dropin.go      | 151 +++++++++++++++++++++++-------------------
 slices/dropin_test.go |  47 +++++++++----
 slices/reverse.go     |   8 ---
 slices/slices.go      |  28 +++++++-
 6 files changed, 146 insertions(+), 92 deletions(-)
 delete mode 100644 slices/reverse.go

diff --git a/go.mod b/go.mod
index c39af09..05847a9 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,7 @@ go 1.18
 
 require (
 	github.com/mattn/go-sqlite3 v1.14.12
-	golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb
+	golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 )
 
diff --git a/go.sum b/go.sum
index 0675c09..3806ad9 100644
--- a/go.sum
+++ b/go.sum
@@ -2,5 +2,7 @@ github.com/mattn/go-sqlite3 v1.14.12 h1:TJ1bhYJPV44phC+IMu1u2K/i5RriLTPe+yc68XDJ
 github.com/mattn/go-sqlite3 v1.14.12/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
 golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb h1:PaBZQdo+iSDyHT053FjUCgZQ/9uqVwPOcl7KSWhKn6w=
 golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
+golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb h1:mIKbk8weKhSeLH2GmUTrvx8CjkyJmnU1wFmg59CUjFA=
+golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
diff --git a/slices/dropin.go b/slices/dropin.go
index 0c3ae24..692e21f 100644
--- a/slices/dropin.go
+++ b/slices/dropin.go
@@ -13,89 +13,70 @@ import (
 // Otherwise, the elements are compared in increasing index order, and the
 // comparison stops at the first unequal pair.
 // Floating point NaNs are not considered equal.
-func Equal[E comparable](s1, s2 []E) bool {
+func Equal[S ~[]E, E comparable](s1, s2 S) bool {
 	return slices.Equal(s1, s2)
 }
 
-// EqualFunc reports whether two slices are equal using a comparison
+// EqualFunc reports whether two slices are equal using an equality
 // function on each pair of elements. If the lengths are different,
 // EqualFunc returns false. Otherwise, the elements are compared in
 // increasing index order, and the comparison stops at the first index
 // for which eq returns false.
-func EqualFunc[E1, E2 any](s1 []E1, s2 []E2, eq func(E1, E2) bool) bool {
+func EqualFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, eq func(E1, E2) bool) bool {
 	return slices.EqualFunc(s1, s2, eq)
 }
 
-// Compare compares the elements of s1 and s2.
-// The elements are compared sequentially, starting at index 0,
+// Compare compares the elements of s1 and s2, using [cmp.Compare] on each pair
+// of elements. The elements are compared sequentially, starting at index 0,
 // until one element is not equal to the other.
 // The result of comparing the first non-matching elements is returned.
 // If both slices are equal until one of them ends, the shorter slice is
 // considered less than the longer one.
 // The result is 0 if s1 == s2, -1 if s1 < s2, and +1 if s1 > s2.
-// Comparisons involving floating point NaNs are ignored.
-func Compare[E constraints.Ordered](s1, s2 []E) int {
+func Compare[S ~[]E, E constraints.Ordered](s1, s2 S) int {
 	return slices.Compare(s1, s2)
 }
 
-// CompareFunc is like Compare but uses a comparison function
-// on each pair of elements. The elements are compared in increasing
-// index order, and the comparisons stop after the first time cmp
-// returns non-zero.
+// CompareFunc is like [Compare] but uses a custom comparison function on each
+// pair of elements.
 // The result is the first non-zero result of cmp; if cmp always
 // returns 0 the result is 0 if len(s1) == len(s2), -1 if len(s1) < len(s2),
 // and +1 if len(s1) > len(s2).
-func CompareFunc[E1, E2 any](s1 []E1, s2 []E2, cmp func(E1, E2) int) int {
+func CompareFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, cmp func(E1, E2) int) int {
 	return slices.CompareFunc(s1, s2, cmp)
 }
 
 // Index returns the index of the first occurrence of v in s,
 // or -1 if not present.
-func Index[E comparable](s []E, v E) int {
+func Index[S ~[]E, E comparable](s S, v E) int {
 	return slices.Index(s, v)
 }
 
 // IndexFunc returns the first index i satisfying f(s[i]),
 // or -1 if none do.
-func IndexFunc[E any](s []E, f func(E) bool) int {
+func IndexFunc[S ~[]E, E any](s S, f func(E) bool) int {
 	return slices.IndexFunc(s, f)
 }
 
 // Contains reports whether v is present in s.
-func Contains[E comparable](s []E, v E) bool {
+func Contains[S ~[]E, E comparable](s S, v E) bool {
 	return slices.Contains(s, v)
 }
 
 // ContainsFunc reports whether at least one
 // element e of s satisfies f(e).
-func ContainsFunc[E any](s []E, f func(E) bool) bool {
+func ContainsFunc[S ~[]E, E any](s S, f func(E) bool) bool {
 	return slices.ContainsFunc(s, f)
 }
 
-// Delete removes the elements s[i:j] from s, returning the modified slice.
-// Delete panics if s[i:j] is not a valid slice of s.
-// Delete modifies the contents of the slice s; it does not create a new slice.
-// Delete is O(len(s)-j), so if many items must be deleted, it is better to
-// make a single call deleting them all together than to delete one at a time.
-// Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those
-// elements contain pointers you might consider zeroing those elements so that
-// objects they reference can be garbage collected.
-//
-// If i < 0 it counts from the end of s.
-// If j <= 0 it counts from the end of s.
-// (This is a change from the behavior of "golang.org/x/exp/slices".Delete.)
-func Delete[S ~[]E, E any](s S, i, j int) S {
-	return RemoveTo(s, i, j)
-}
-
-// Replace replaces the elements s[i:j] by the given v, and returns the
-// modified slice. Replace panics if s[i:j] is not a valid slice of s.
-//
-// If i < 0 it counts from the end of s.
-// If j <= 0 it counts from the end of s.
-// (This is a change from the behavior of "golang.org/x/exp/slices".Replace.)
-func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
-	return ReplaceTo(s, i, j, v...)
+// DeleteFunc removes any elements from s for which del returns true,
+// returning the modified slice.
+// When DeleteFunc removes m elements, it might not modify the elements
+// s[len(s)-m:len(s)]. If those elements contain pointers you might consider
+// zeroing those elements so that objects they reference can be garbage
+// collected.
+func DeleteFunc[S ~[]E, E any](s S, del func(E) bool) S {
+	return slices.DeleteFunc(s, del)
 }
 
 // Clone returns a copy of the slice.
@@ -106,7 +87,8 @@ func Clone[S ~[]E, E any](s S) S {
 
 // Compact replaces consecutive runs of equal elements with a single copy.
 // This is like the uniq command found on Unix.
-// Compact modifies the contents of the slice s; it does not create a new slice.
+// Compact modifies the contents of the slice s and returns the modified slice,
+// which may have a smaller length.
 // When Compact discards m elements in total, it might not modify the elements
 // s[len(s)-m:len(s)]. If those elements contain pointers you might consider
 // zeroing those elements so that objects they reference can be garbage collected.
@@ -114,7 +96,8 @@ func Compact[S ~[]E, E comparable](s S) S {
 	return slices.Compact(s)
 }
 
-// CompactFunc is like Compact but uses a comparison function.
+// CompactFunc is like [Compact] but uses an equality function to compare elements.
+// For runs of elements that compare equal, CompactFunc keeps the first one.
 func CompactFunc[S ~[]E, E any](s S, eq func(E, E) bool) S {
 	return slices.CompactFunc(s, eq)
 }
@@ -132,54 +115,88 @@ func Clip[S ~[]E, E any](s S) S {
 	return slices.Clip(s)
 }
 
+// Reverse reverses the elements of the slice in place.
+func Reverse[S ~[]E, E any](s S) {
+	slices.Reverse(s)
+}
+
 // Sort sorts a slice of any ordered type in ascending order.
-// Sort may fail to sort correctly when sorting slices of floating-point
-// numbers containing Not-a-number (NaN) values.
-// Use slices.SortFunc(x, func(a, b float64) bool {return a < b || (math.IsNaN(a) && !math.IsNaN(b))})
-// instead if the input may contain NaNs.
-func Sort[E constraints.Ordered](x []E) {
+// When sorting floating-point numbers, NaNs are ordered before other values.
+func Sort[S ~[]E, E constraints.Ordered](x S) {
 	slices.Sort(x)
 }
 
-// SortFunc sorts the slice x in ascending order as determined by the less function.
-// This sort is not guaranteed to be stable.
+// SortFunc sorts the slice x in ascending order as determined by the cmp
+// function. This sort is not guaranteed to be stable.
+// cmp(a, b) should return a negative number when a < b, a positive number when
+// a > b and zero when a == b.
 //
-// SortFunc requires that less is a strict weak ordering.
+// SortFunc requires that cmp is a strict weak ordering.
 // See https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings.
-func SortFunc[E any](x []E, less func(a, b E) bool) {
-	slices.SortFunc(x, less)
+func SortFunc[S ~[]E, E any](x S, cmp func(a, b E) int) {
+	slices.SortFunc(x, cmp)
 }
 
 // SortStableFunc sorts the slice x while keeping the original order of equal
-// elements, using less to compare elements.
-func SortStableFunc[E any](x []E, less func(a, b E) bool) {
-	slices.SortStableFunc(x, less)
+// elements, using cmp to compare elements in the same way as [SortFunc].
+func SortStableFunc[S ~[]E, E any](x S, cmp func(a, b E) int) {
+	slices.SortStableFunc(x, cmp)
 }
 
 // IsSorted reports whether x is sorted in ascending order.
-func IsSorted[E constraints.Ordered](x []E) bool {
+func IsSorted[S ~[]E, E constraints.Ordered](x S) bool {
 	return slices.IsSorted(x)
 }
 
-// IsSortedFunc reports whether x is sorted in ascending order, with less as the
-// comparison function.
-func IsSortedFunc[E any](x []E, less func(a, b E) bool) bool {
-	return slices.IsSortedFunc(x, less)
+// IsSortedFunc reports whether x is sorted in ascending order, with cmp as the
+// comparison function as defined by [SortFunc].
+func IsSortedFunc[S ~[]E, E any](x S, cmp func(a, b E) int) bool {
+	return slices.IsSortedFunc(x, cmp)
+}
+
+// Min returns the minimal value in x. It panics if x is empty.
+// For floating-point numbers, Min propagates NaNs (any NaN value in x
+// forces the output to be NaN).
+func Min[S ~[]E, E constraints.Ordered](x S) E {
+	return slices.Min(x)
+}
+
+// MinFunc returns the minimal value in x, using cmp to compare elements.
+// It panics if x is empty. If there is more than one minimal element
+// according to the cmp function, MinFunc returns the first one.
+func MinFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E {
+	return slices.MinFunc(x, cmp)
+}
+
+// Max returns the maximal value in x. It panics if x is empty.
+// For floating-point E, Max propagates NaNs (any NaN value in x
+// forces the output to be NaN).
+func Max[S ~[]E, E constraints.Ordered](x S) E {
+	return slices.Max(x)
+}
+
+// MaxFunc returns the maximal value in x, using cmp to compare elements.
+// It panics if x is empty. If there is more than one maximal element
+// according to the cmp function, MaxFunc returns the first one.
+func MaxFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E {
+	return slices.MaxFunc(x, cmp)
 }
 
 // BinarySearch searches for target in a sorted slice and returns the position
 // where target is found, or the position where target would appear in the
 // sort order; it also returns a bool saying whether the target is really found
 // in the slice. The slice must be sorted in increasing order.
-func BinarySearch[E constraints.Ordered](x []E, target E) (int, bool) {
+func BinarySearch[S ~[]E, E constraints.Ordered](x S, target E) (int, bool) {
 	return slices.BinarySearch(x, target)
 }
 
-// BinarySearchFunc works like BinarySearch, but uses a custom comparison
-// function. The slice must be sorted in increasing order, where "increasing" is
-// defined by cmp. cmp(a, b) is expected to return an integer comparing the two
-// parameters: 0 if a == b, a negative number if a < b and a positive number if
-// a > b.
-func BinarySearchFunc[E, T any](x []E, target T, cmp func(E, T) int) (int, bool) {
+// BinarySearchFunc works like [BinarySearch], but uses a custom comparison
+// function. The slice must be sorted in increasing order, where "increasing"
+// is defined by cmp. cmp should return 0 if the slice element matches
+// the target, a negative number if the slice element precedes the target,
+// or a positive number if the slice element follows the target.
+// cmp must implement the same ordering as the slice, such that if
+// cmp(a, t) < 0 and cmp(b, t) >= 0, then a must precede b in the slice.
+func BinarySearchFunc[S ~[]E, E, T any](x S, target T, cmp func(E, T) int) (int, bool) {
 	return slices.BinarySearchFunc(x, target, cmp)
 }
diff --git a/slices/dropin_test.go b/slices/dropin_test.go
index 9fc300c..7ffd864 100644
--- a/slices/dropin_test.go
+++ b/slices/dropin_test.go
@@ -179,12 +179,12 @@ var compareFloatTests = []struct {
 	{
 		[]float64{1, math.NaN(), 3},
 		[]float64{1, 2, math.NaN()},
-		0,
+		-1,
 	},
 	{
 		[]float64{1, math.NaN(), 3, 4},
 		[]float64{1, 2, math.NaN()},
-		+1,
+		-1,
 	},
 }
 
@@ -237,6 +237,25 @@ func cmp[T constraints.Ordered](v1, v2 T) int {
 	}
 }
 
+func cmpfloat64(a, b float64) int {
+	if math.IsNaN(a) {
+		if math.IsNaN(b) {
+			return 0
+		}
+		return -1
+	}
+	if math.IsNaN(b) {
+		return 1
+	}
+	if a < b {
+		return -1
+	}
+	if a > b {
+		return 1
+	}
+	return 0
+}
+
 func TestCompareFunc(t *testing.T) {
 	intWant := func(want bool) string {
 		if want {
@@ -261,8 +280,8 @@ func TestCompareFunc(t *testing.T) {
 		}
 	}
 	for _, test := range compareFloatTests {
-		if got := CompareFunc(test.s1, test.s2, cmp[float64]); got != test.want {
-			t.Errorf("CompareFunc(%v, %v, cmp[float64]) = %d, want %d", test.s1, test.s2, got, test.want)
+		if got := CompareFunc(test.s1, test.s2, cmpfloat64); got != test.want {
+			t.Errorf("CompareFunc(%v, %v, cmpfloat64) = %d, want %d", test.s1, test.s2, got, test.want)
 		}
 	}
 
@@ -724,7 +743,7 @@ func TestSortIntSlice(t *testing.T) {
 
 func TestSortFuncIntSlice(t *testing.T) {
 	data := Clone(ints[:])
-	SortFunc(data, func(a, b int) bool { return a < b })
+	SortFunc(data, func(a, b int) int { return a - b })
 	if !IsSorted(data) {
 		t.Errorf("sorted %v", ints)
 		t.Errorf("   got %v", data)
@@ -790,8 +809,8 @@ type intPair struct {
 type intPairs []intPair
 
 // Pairs compare on a only.
-func intPairLess(x, y intPair) bool {
-	return x.a < y.a
+func intPairCmp(x, y intPair) int {
+	return x.a - y.a
 }
 
 // Record initial order in B.
@@ -829,12 +848,12 @@ func TestStability(t *testing.T) {
 	for i := 0; i < len(data); i++ {
 		data[i].a = rand.Intn(m)
 	}
-	if IsSortedFunc(data, intPairLess) {
+	if IsSortedFunc(data, intPairCmp) {
 		t.Fatalf("terrible rand.rand")
 	}
 	data.initB()
-	SortStableFunc(data, intPairLess)
-	if !IsSortedFunc(data, intPairLess) {
+	SortStableFunc(data, intPairCmp)
+	if !IsSortedFunc(data, intPairCmp) {
 		t.Errorf("Stable didn't sort %d ints", n)
 	}
 	if !data.inOrder() {
@@ -843,8 +862,8 @@ func TestStability(t *testing.T) {
 
 	// already sorted
 	data.initB()
-	SortStableFunc(data, intPairLess)
-	if !IsSortedFunc(data, intPairLess) {
+	SortStableFunc(data, intPairCmp)
+	if !IsSortedFunc(data, intPairCmp) {
 		t.Errorf("Stable shuffled sorted %d ints (order)", n)
 	}
 	if !data.inOrder() {
@@ -856,8 +875,8 @@ func TestStability(t *testing.T) {
 		data[i].a = len(data) - i
 	}
 	data.initB()
-	SortStableFunc(data, intPairLess)
-	if !IsSortedFunc(data, intPairLess) {
+	SortStableFunc(data, intPairCmp)
+	if !IsSortedFunc(data, intPairCmp) {
 		t.Errorf("Stable didn't sort %d ints", n)
 	}
 	if !data.inOrder() {
diff --git a/slices/reverse.go b/slices/reverse.go
deleted file mode 100644
index 882b8b9..0000000
--- a/slices/reverse.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package slices
-
-// Reverse reverses a slice in place.
-func Reverse[S ~[]T, T any](s S) {
-	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
-		s[i], s[j] = s[j], s[i]
-	}
-}
diff --git a/slices/slices.go b/slices/slices.go
index e493de1..6364685 100644
--- a/slices/slices.go
+++ b/slices/slices.go
@@ -19,7 +19,6 @@ package slices
 import (
 	"sort"
 
-	// TODO: import slices from stdlib after Go 1.21.
 	"golang.org/x/exp/slices"
 
 	"github.com/bobg/go-generics/v2/internal"
@@ -56,7 +55,7 @@ func Append[S ~[]T, T any](s S, vals ...T) S {
 // After the insert, the first new value has position idx.
 //
 // If idx < 0, it counts from the end of s.
-// (This is a change from the behavior of "golang.org/x/exp/slices".Insert.)
+// (This is a change from the behavior of Go's standard slices.Insert.)
 //
 // The input slice is modified.
 //
@@ -68,6 +67,31 @@ func Insert[S ~[]T, T any](s S, idx int, vals ...T) S {
 	return slices.Insert(s, idx, vals...)
 }
 
+// Delete removes the elements s[i:j] from s, returning the modified slice.
+// Delete panics if s[i:j] is not a valid slice of s.
+// Delete is O(len(s)-j), so if many items must be deleted, it is better to
+// make a single call deleting them all together than to delete one at a time.
+// Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those
+// elements contain pointers you might consider zeroing those elements so that
+// objects they reference can be garbage collected.
+//
+// If i < 0 it counts from the end of s.
+// If j <= 0 it counts from the end of s.
+// (This is a change from the behavior of Go's standard slices.Delete.)
+func Delete[S ~[]E, E any](s S, i, j int) S {
+	return RemoveTo(s, i, j)
+}
+
+// Replace replaces the elements s[i:j] by the given v, and returns the
+// modified slice. Replace panics if s[i:j] is not a valid slice of s.
+//
+// If i < 0 it counts from the end of s.
+// If j <= 0 it counts from the end of s.
+// (This is a change from the behavior of "golang.org/x/exp/slices".Replace.)
+func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
+	return ReplaceTo(s, i, j, v...)
+}
+
 // ReplaceN replaces the n values of s beginning at position idx with the given values.
 // After the replace, the first new value has position idx.
 //

From c588025ff76c8af7ab4d25a7e23ee44d359a807f Mon Sep 17 00:00:00 2001
From: Bob Glickstein <bobg@emphatic.com>
Date: Sun, 13 Aug 2023 11:53:00 -0700
Subject: [PATCH 2/4] Implement in terms of new slices, maps, and cmp packages;
 require Go 1.21.

---
 go.mod                       |  6 ++---
 iter/example_test.go         |  2 +-
 iter/n.go                    |  2 +-
 maps/dropin.go               | 21 ++--------------
 maps/dropin_test.go          |  2 +-
 maps/maps.go                 | 29 +++++++++++++++++++++-
 maps/maps_test.go            |  2 +-
 parallel/example_test.go     |  2 +-
 parallel/parallel.go         |  2 +-
 parallel/parallel_test.go    |  2 +-
 set/example_test.go          |  2 +-
 set/set.go                   |  4 +--
 slices/combinatorics.go      |  2 +-
 slices/combinatorics_test.go |  2 +-
 slices/dropin.go             | 18 +++++++-------
 slices/dropin_test.go        | 48 +++++++-----------------------------
 slices/example_test.go       |  2 +-
 slices/slices.go             |  7 +++---
 18 files changed, 66 insertions(+), 89 deletions(-)

diff --git a/go.mod b/go.mod
index 05847a9..817f9d0 100644
--- a/go.mod
+++ b/go.mod
@@ -1,11 +1,9 @@
-module github.com/bobg/go-generics/v2
+module github.com/bobg/go-generics/v3
 
-go 1.18
+go 1.21
 
 require (
 	github.com/mattn/go-sqlite3 v1.14.12
 	golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 )
-
-retract v2.0.0
diff --git a/iter/example_test.go b/iter/example_test.go
index 61c8ca4..da4bbae 100644
--- a/iter/example_test.go
+++ b/iter/example_test.go
@@ -3,7 +3,7 @@ package iter_test
 import (
 	"fmt"
 
-	"github.com/bobg/go-generics/v2/iter"
+	"github.com/bobg/go-generics/v3/iter"
 )
 
 func ExampleAccum() {
diff --git a/iter/n.go b/iter/n.go
index b70f9a2..db47db7 100644
--- a/iter/n.go
+++ b/iter/n.go
@@ -1,6 +1,6 @@
 package iter
 
-import "github.com/bobg/go-generics/v2/internal"
+import "github.com/bobg/go-generics/v3/internal"
 
 // FirstN produces an iterator containing the first n elements of the input
 // (or all of the input, if there are fewer than n elements).
diff --git a/maps/dropin.go b/maps/dropin.go
index 3090d48..232cc81 100644
--- a/maps/dropin.go
+++ b/maps/dropin.go
@@ -1,20 +1,8 @@
 package maps
 
-import "golang.org/x/exp/maps"
+import "maps"
 
-// This file contains entrypoints for each of the functions in in golang.org/x/exp/maps.
-
-// Keys returns the keys of the map m.
-// The keys will be in an indeterminate order.
-func Keys[M ~map[K]V, K comparable, V any](m M) []K {
-	return maps.Keys(m)
-}
-
-// Values returns the values of the map m.
-// The values will be in an indeterminate order.
-func Values[M ~map[K]V, K comparable, V any](m M) []V {
-	return maps.Values(m)
-}
+// This file contains entrypoints for each of the functions in the standard Go maps package.
 
 // Equal reports whether two maps contain the same key/value pairs.
 // Values are compared using ==.
@@ -28,11 +16,6 @@ func EqualFunc[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M
 	return maps.EqualFunc(m1, m2, eq)
 }
 
-// Clear removes all entries from m, leaving it empty.
-func Clear[M ~map[K]V, K comparable, V any](m M) {
-	maps.Clear(m)
-}
-
 // Clone returns a copy of m.  This is a shallow clone:
 // the new keys and values are set using ordinary assignment.
 func Clone[M ~map[K]V, K comparable, V any](m M) M {
diff --git a/maps/dropin_test.go b/maps/dropin_test.go
index 1297e69..61c4cc9 100644
--- a/maps/dropin_test.go
+++ b/maps/dropin_test.go
@@ -12,7 +12,7 @@ import (
 	"strconv"
 	"testing"
 
-	"github.com/bobg/go-generics/v2/slices"
+	"github.com/bobg/go-generics/v3/slices"
 )
 
 var m1 = map[int]int{1: 2, 2: 4, 4: 8, 8: 16}
diff --git a/maps/maps.go b/maps/maps.go
index f2de7d5..342dc74 100644
--- a/maps/maps.go
+++ b/maps/maps.go
@@ -8,7 +8,7 @@
 // in Go 1.21 (https://go.dev/doc/go1.21#maps).
 package maps
 
-import "github.com/bobg/go-generics/v2/iter"
+import "github.com/bobg/go-generics/v3/iter"
 
 // Each calls a function on each key-value pair in the given map.
 func Each[M ~map[K]V, K comparable, V any](m M, f func(K, V)) {
@@ -63,3 +63,30 @@ func InvertMulti[M ~map[K]V, K, V comparable](m M) map[V][]K {
 	}
 	return result
 }
+
+// Keys returns the keys of the map m.
+// The keys will be in an indeterminate order.
+func Keys[M ~map[K]V, K comparable, V any](m M) []K {
+	result := make([]K, 0, len(m))
+	for k := range m {
+		result = append(result, k)
+	}
+	return result
+}
+
+// Values returns the values of the map m.
+// The values will be in an indeterminate order.
+func Values[M ~map[K]V, K comparable, V any](m M) []V {
+	result := make([]V, 0, len(m))
+	for _, v := range m {
+		result = append(result, v)
+	}
+	return result
+}
+
+// Clear removes all entries from m, leaving it empty.
+func Clear[M ~map[K]V, K comparable, V any](m M) {
+	for k := range m {
+		delete(m, k)
+	}
+}
diff --git a/maps/maps_test.go b/maps/maps_test.go
index ec61872..24b7853 100644
--- a/maps/maps_test.go
+++ b/maps/maps_test.go
@@ -4,7 +4,7 @@ import (
 	"reflect"
 	"testing"
 
-	"github.com/bobg/go-generics/v2/iter"
+	"github.com/bobg/go-generics/v3/iter"
 )
 
 var (
diff --git a/parallel/example_test.go b/parallel/example_test.go
index 1f19e16..ae4fc83 100644
--- a/parallel/example_test.go
+++ b/parallel/example_test.go
@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"sync"
 
-	"github.com/bobg/go-generics/v2/parallel"
+	"github.com/bobg/go-generics/v3/parallel"
 )
 
 func ExampleConsumers() {
diff --git a/parallel/parallel.go b/parallel/parallel.go
index 69d164f..9097889 100644
--- a/parallel/parallel.go
+++ b/parallel/parallel.go
@@ -8,7 +8,7 @@ import (
 
 	"golang.org/x/sync/errgroup"
 
-	"github.com/bobg/go-generics/v2/iter"
+	"github.com/bobg/go-generics/v3/iter"
 )
 
 // Error is an error type for wrapping errors returned from worker goroutines.
diff --git a/parallel/parallel_test.go b/parallel/parallel_test.go
index f60dd84..91bc4be 100644
--- a/parallel/parallel_test.go
+++ b/parallel/parallel_test.go
@@ -6,7 +6,7 @@ import (
 	"sync"
 	"testing"
 
-	"github.com/bobg/go-generics/v2/set"
+	"github.com/bobg/go-generics/v3/set"
 )
 
 func TestValues(t *testing.T) {
diff --git a/set/example_test.go b/set/example_test.go
index 1a64c45..8242571 100644
--- a/set/example_test.go
+++ b/set/example_test.go
@@ -3,7 +3,7 @@ package set_test
 import (
 	"fmt"
 
-	"github.com/bobg/go-generics/v2/set"
+	"github.com/bobg/go-generics/v3/set"
 )
 
 func ExampleDiff() {
diff --git a/set/set.go b/set/set.go
index 9b8871d..12ce2fb 100644
--- a/set/set.go
+++ b/set/set.go
@@ -2,8 +2,8 @@
 package set
 
 import (
-	"github.com/bobg/go-generics/v2/iter"
-	"github.com/bobg/go-generics/v2/maps"
+	"github.com/bobg/go-generics/v3/iter"
+	"github.com/bobg/go-generics/v3/maps"
 )
 
 // Of is a set of elements of type T.
diff --git a/slices/combinatorics.go b/slices/combinatorics.go
index 004aee2..6f25e38 100644
--- a/slices/combinatorics.go
+++ b/slices/combinatorics.go
@@ -1,7 +1,7 @@
 package slices
 
 import (
-	"github.com/bobg/go-generics/v2/iter"
+	"github.com/bobg/go-generics/v3/iter"
 )
 
 // Permutations produces an iterator over all permutations of s.
diff --git a/slices/combinatorics_test.go b/slices/combinatorics_test.go
index 28bcd48..1b6631d 100644
--- a/slices/combinatorics_test.go
+++ b/slices/combinatorics_test.go
@@ -5,7 +5,7 @@ import (
 	"reflect"
 	"testing"
 
-	"github.com/bobg/go-generics/v2/iter"
+	"github.com/bobg/go-generics/v3/iter"
 )
 
 func TestPermutations(t *testing.T) {
diff --git a/slices/dropin.go b/slices/dropin.go
index 692e21f..cee2ca7 100644
--- a/slices/dropin.go
+++ b/slices/dropin.go
@@ -1,11 +1,11 @@
 package slices
 
 import (
-	"golang.org/x/exp/constraints"
-	"golang.org/x/exp/slices"
+	"cmp"
+	"slices"
 )
 
-// This file contains entrypoints for each of the functions in in golang.org/x/exp/slices
+// This file contains entrypoints for each of the functions in the standard Go slices package
 // (except those, like Insert, extended by other functions in this package).
 
 // Equal reports whether two slices are equal: the same length and all
@@ -33,7 +33,7 @@ func EqualFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, eq func(E1, E2) boo
 // If both slices are equal until one of them ends, the shorter slice is
 // considered less than the longer one.
 // The result is 0 if s1 == s2, -1 if s1 < s2, and +1 if s1 > s2.
-func Compare[S ~[]E, E constraints.Ordered](s1, s2 S) int {
+func Compare[S ~[]E, E cmp.Ordered](s1, s2 S) int {
 	return slices.Compare(s1, s2)
 }
 
@@ -122,7 +122,7 @@ func Reverse[S ~[]E, E any](s S) {
 
 // Sort sorts a slice of any ordered type in ascending order.
 // When sorting floating-point numbers, NaNs are ordered before other values.
-func Sort[S ~[]E, E constraints.Ordered](x S) {
+func Sort[S ~[]E, E cmp.Ordered](x S) {
 	slices.Sort(x)
 }
 
@@ -144,7 +144,7 @@ func SortStableFunc[S ~[]E, E any](x S, cmp func(a, b E) int) {
 }
 
 // IsSorted reports whether x is sorted in ascending order.
-func IsSorted[S ~[]E, E constraints.Ordered](x S) bool {
+func IsSorted[S ~[]E, E cmp.Ordered](x S) bool {
 	return slices.IsSorted(x)
 }
 
@@ -157,7 +157,7 @@ func IsSortedFunc[S ~[]E, E any](x S, cmp func(a, b E) int) bool {
 // Min returns the minimal value in x. It panics if x is empty.
 // For floating-point numbers, Min propagates NaNs (any NaN value in x
 // forces the output to be NaN).
-func Min[S ~[]E, E constraints.Ordered](x S) E {
+func Min[S ~[]E, E cmp.Ordered](x S) E {
 	return slices.Min(x)
 }
 
@@ -171,7 +171,7 @@ func MinFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E {
 // Max returns the maximal value in x. It panics if x is empty.
 // For floating-point E, Max propagates NaNs (any NaN value in x
 // forces the output to be NaN).
-func Max[S ~[]E, E constraints.Ordered](x S) E {
+func Max[S ~[]E, E cmp.Ordered](x S) E {
 	return slices.Max(x)
 }
 
@@ -186,7 +186,7 @@ func MaxFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E {
 // where target is found, or the position where target would appear in the
 // sort order; it also returns a bool saying whether the target is really found
 // in the slice. The slice must be sorted in increasing order.
-func BinarySearch[S ~[]E, E constraints.Ordered](x S, target E) (int, bool) {
+func BinarySearch[S ~[]E, E cmp.Ordered](x S, target E) (int, bool) {
 	return slices.BinarySearch(x, target)
 }
 
diff --git a/slices/dropin_test.go b/slices/dropin_test.go
index 7ffd864..ea30e55 100644
--- a/slices/dropin_test.go
+++ b/slices/dropin_test.go
@@ -7,14 +7,13 @@
 package slices
 
 import (
+	"cmp"
 	"math"
 	"math/rand"
 	"sort"
 	"strconv"
 	"strings"
 	"testing"
-
-	"golang.org/x/exp/constraints"
 )
 
 var raceEnabled bool
@@ -89,7 +88,7 @@ func equalNaN[T comparable](v1, v2 T) bool {
 }
 
 // offByOne returns true if integers v1 and v2 differ by 1.
-func offByOne[E constraints.Integer](v1, v2 E) bool {
+func offByOne(v1, v2 int) bool {
 	return v1 == v2+1 || v1 == v2-1
 }
 
@@ -110,10 +109,10 @@ func TestEqualFunc(t *testing.T) {
 
 	s1 := []int{1, 2, 3}
 	s2 := []int{2, 3, 4}
-	if EqualFunc(s1, s1, offByOne[int]) {
+	if EqualFunc(s1, s1, offByOne) {
 		t.Errorf("EqualFunc(%v, %v, offByOne) = true, want false", s1, s1)
 	}
-	if !EqualFunc(s1, s2, offByOne[int]) {
+	if !EqualFunc(s1, s2, offByOne) {
 		t.Errorf("EqualFunc(%v, %v, offByOne) = false, want true", s1, s2)
 	}
 
@@ -227,35 +226,6 @@ func equalToCmp[T comparable](eq func(T, T) bool) func(T, T) int {
 	}
 }
 
-func cmp[T constraints.Ordered](v1, v2 T) int {
-	if v1 < v2 {
-		return -1
-	} else if v1 > v2 {
-		return 1
-	} else {
-		return 0
-	}
-}
-
-func cmpfloat64(a, b float64) int {
-	if math.IsNaN(a) {
-		if math.IsNaN(b) {
-			return 0
-		}
-		return -1
-	}
-	if math.IsNaN(b) {
-		return 1
-	}
-	if a < b {
-		return -1
-	}
-	if a > b {
-		return 1
-	}
-	return 0
-}
-
 func TestCompareFunc(t *testing.T) {
 	intWant := func(want bool) string {
 		if want {
@@ -275,19 +245,19 @@ func TestCompareFunc(t *testing.T) {
 	}
 
 	for _, test := range compareIntTests {
-		if got := CompareFunc(test.s1, test.s2, cmp[int]); got != test.want {
-			t.Errorf("CompareFunc(%v, %v, cmp[int]) = %d, want %d", test.s1, test.s2, got, test.want)
+		if got := CompareFunc(test.s1, test.s2, cmp.Compare); got != test.want {
+			t.Errorf("CompareFunc(%v, %v, cmp.Compare) = %d, want %d", test.s1, test.s2, got, test.want)
 		}
 	}
 	for _, test := range compareFloatTests {
-		if got := CompareFunc(test.s1, test.s2, cmpfloat64); got != test.want {
-			t.Errorf("CompareFunc(%v, %v, cmpfloat64) = %d, want %d", test.s1, test.s2, got, test.want)
+		if got := CompareFunc(test.s1, test.s2, cmp.Compare); got != test.want {
+			t.Errorf("CompareFunc(%v, %v, cmp.Compare) = %d, want %d", test.s1, test.s2, got, test.want)
 		}
 	}
 
 	s1 := []int{1, 2, 3}
 	s2 := []int{2, 3, 4}
-	if got := CompareFunc(s1, s2, equalToCmp(offByOne[int])); got != 0 {
+	if got := CompareFunc(s1, s2, equalToCmp(offByOne)); got != 0 {
 		t.Errorf("CompareFunc(%v, %v, offByOne) = %d, want 0", s1, s2, got)
 	}
 
diff --git a/slices/example_test.go b/slices/example_test.go
index 8608f72..d1ae7a7 100644
--- a/slices/example_test.go
+++ b/slices/example_test.go
@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"sort"
 
-	"github.com/bobg/go-generics/v2/slices"
+	"github.com/bobg/go-generics/v3/slices"
 )
 
 func ExampleGet() {
diff --git a/slices/slices.go b/slices/slices.go
index 6364685..14b6463 100644
--- a/slices/slices.go
+++ b/slices/slices.go
@@ -17,11 +17,10 @@
 package slices
 
 import (
+	"slices"
 	"sort"
 
-	"golang.org/x/exp/slices"
-
-	"github.com/bobg/go-generics/v2/internal"
+	"github.com/bobg/go-generics/v3/internal"
 )
 
 // Get gets the idx'th element of s.
@@ -87,7 +86,7 @@ func Delete[S ~[]E, E any](s S, i, j int) S {
 //
 // If i < 0 it counts from the end of s.
 // If j <= 0 it counts from the end of s.
-// (This is a change from the behavior of "golang.org/x/exp/slices".Replace.)
+// (This is a change from the behavior of Go's standard slices.Replace.)
 func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
 	return ReplaceTo(s, i, j, v...)
 }

From 08d82362968d5ce1bcb57710b9a54736ea18e8fa Mon Sep 17 00:00:00 2001
From: Bob Glickstein <bobg@emphatic.com>
Date: Sun, 13 Aug 2023 11:55:14 -0700
Subject: [PATCH 3/4] Remove x/exp dependency.

---
 go.mod | 1 -
 go.sum | 4 ----
 2 files changed, 5 deletions(-)

diff --git a/go.mod b/go.mod
index 817f9d0..1d664f9 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,5 @@ go 1.21
 
 require (
 	github.com/mattn/go-sqlite3 v1.14.12
-	golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 )
diff --git a/go.sum b/go.sum
index 3806ad9..fc0f3e1 100644
--- a/go.sum
+++ b/go.sum
@@ -1,8 +1,4 @@
 github.com/mattn/go-sqlite3 v1.14.12 h1:TJ1bhYJPV44phC+IMu1u2K/i5RriLTPe+yc68XDJ1Z0=
 github.com/mattn/go-sqlite3 v1.14.12/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
-golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb h1:PaBZQdo+iSDyHT053FjUCgZQ/9uqVwPOcl7KSWhKn6w=
-golang.org/x/exp v0.0.0-20230213192124-5e25df0256eb/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
-golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb h1:mIKbk8weKhSeLH2GmUTrvx8CjkyJmnU1wFmg59CUjFA=
-golang.org/x/exp v0.0.0-20230811145659-89c5cff77bcb/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

From 2ab275a4bab5235dc2ccbde42a0715809b22d350 Mon Sep 17 00:00:00 2001
From: Bob Glickstein <bobg@emphatic.com>
Date: Sun, 13 Aug 2023 11:56:35 -0700
Subject: [PATCH 4/4] Require Go 1.21 in CI.

---
 .github/workflows/go.yml            | 2 +-
 .github/workflows/golangci-lint.yml | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 009004b..9202232 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -15,7 +15,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.18
+        go-version: 1.21
 
     - name: Unit tests
       run: go test -v -coverprofile=cover.out ./...
diff --git a/.github/workflows/golangci-lint.yml b/.github/workflows/golangci-lint.yml
index c35dd89..096cc03 100644
--- a/.github/workflows/golangci-lint.yml
+++ b/.github/workflows/golangci-lint.yml
@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/setup-go@v3
         with:
-          go-version: '1.18'
+          go-version: '1.21'
       - uses: actions/checkout@v3
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v3