feat: add issorted (#152)

README.md

@@ -92,6 +92,8 @@ Supported helpers for slices:
 - [Replace](#replace)
 - [ReplaceAll](#replaceall)
 - [Compact](#compact)
+- [IsSorted](#issorted)
+- [IsSortedByKey](#issortedbykey)
 
 Supported helpers for maps:
 

go.mod

@@ -3,7 +3,7 @@ module github.com/samber/lo
 go 1.18
 
 require (
-	github.com/stretchr/testify v1.7.0
+	github.com/stretchr/testify v1.7.1
 	github.com/thoas/go-funk v0.9.1
 	golang.org/x/exp v0.0.0-20220303212507-bbda1eaf7a17
 )
@@ -14,5 +14,5 @@ require (
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -12,8 +12,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/thoas/go-funk v0.9.1 h1:O549iLZqPpTUQ10ykd26sZhzD+rmR5pWhuElrhbC20M=
 github.com/thoas/go-funk v0.9.1/go.mod h1:+IWnUfUmFO1+WVYQWQtIJHeRRdaIyyYglZN7xzUPe4Q=
 golang.org/x/exp v0.0.0-20220303212507-bbda1eaf7a17 h1:3MTrJm4PyNL9NBqvYDSj3DHl46qQakyfqfWo4jgfaEM=
@@ -23,5 +23,5 @@ gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8X
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

slice.go

@@ -2,6 +2,8 @@ package lo
 
 import (
 	"math/rand"
+
+	"golang.org/x/exp/constraints"
 )
 
 // Filter iterates over elements of collection, returning an array of all elements predicate returns truthy for.
@@ -446,6 +448,31 @@ func ReplaceAll[T comparable](collection []T, old T, new T) []T {
 	return Replace(collection, old, new, -1)
 }
 
+
+// IsSorted checks if a slice is sorted.
+func IsSorted[T constraints.Ordered](collection []T) bool {
+	for i := 1; i < len(collection); i++ {
+		if collection[i-1] > collection[i] {
+			return false
+		}
+	}
+
+	return true
+}
+
+// IsSortedBy checks if a slice is sorted by iteratee.
+func IsSortedByKey[K constraints.Ordered, V any](collection []V, iteratee func(V) K) bool {
+	size := len(collection)
+
+	for i := 0; i < size-1; i++ {
+		if iteratee(collection[i]) > iteratee(collection[i+1]) {
+			return false
+		}
+	}
+
+	return true
+}
+
 // Compact returns a slice of all non-zero elements.
 func Compact[T comparable](collection []T) []T {
 	var zero T

slice_test.go

@@ -503,6 +503,33 @@ func TestReplaceAll(t *testing.T) {
 	is.Equal([]int{0, 1, 0, 1, 2, 3, 0}, out2)
 }
 
+func TestIsSorted(t *testing.T) {
+	is := assert.New(t)
+
+	is.True(IsSorted([]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}))
+	is.True(IsSorted([]string{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"}))
+
+	is.False(IsSorted([]int{0, 1, 4, 3, 2, 5, 6, 7, 8, 9, 10}))
+	is.False(IsSorted([]string{"a", "b", "d", "c", "e", "f", "g", "h", "i", "j"}))
+}
+
+func TestIsSortedByKey(t *testing.T) {
+	is := assert.New(t)
+
+	is.True(IsSortedByKey([]string{"a", "bb", "ccc"}, func(s string) int {
+		return len(s)
+	}))
+
+	is.False(IsSortedByKey([]string{"aa", "b", "ccc"}, func(s string) int {
+		return len(s)
+	}))
+
+	is.True(IsSortedByKey([]string{"1", "2", "3", "11"}, func(s string) int {
+		ret, _ := strconv.Atoi(s)
+		return ret
+	}))
+}
+
 func TestCompact(t *testing.T) {
 	is := assert.New(t)