Migrate to Go 1.18 (#45)

* Migrate to Go 1.18 and add linters

caql/set.go

@@ -22,19 +22,18 @@
 
 package caql
 
-import "sort"
-
-type (
-	Set struct {
-		hash map[interface{}]nothing
-	}
-
-	nothing struct{}
+import (
+	"sort"
 )
 
-// Create a new set
-func New(initial ...interface{}) *Set {
-	s := &Set{make(map[interface{}]nothing)}
+type Set struct {
+	hash map[any]nothing
+}
+
+type nothing struct{}
+
+func NewSet(initial ...any) *Set {
+	s := &Set{make(map[any]nothing)}
 
 	for _, v := range initial {
 		s.Insert(v)
@@ -43,9 +42,8 @@ func New(initial ...interface{}) *Set {
 	return s
 }
 
-// Find the difference between two sets
 func (s *Set) Difference(set *Set) *Set {
-	n := make(map[interface{}]nothing)
+	n := make(map[any]nothing)
 
 	for k := range s.hash {
 		if _, exists := set.hash[k]; !exists {
@@ -56,27 +54,18 @@ func (s *Set) Difference(set *Set) *Set {
 	return &Set{n}
 }
 
-// Call f for each item in the set
-func (s *Set) Do(f func(interface{})) {
-	for k := range s.hash {
-		f(k)
-	}
-}
-
-// Test to see whether or not the element is in the set
-func (s *Set) Has(element interface{}) bool {
+func (s *Set) Has(element any) bool {
 	_, exists := s.hash[element]
+
 	return exists
 }
 
-// Add an element to the set
-func (s *Set) Insert(element interface{}) {
+func (s *Set) Insert(element any) {
 	s.hash[element] = nothing{}
 }
 
-// Find the intersection of two sets
 func (s *Set) Intersection(set *Set) *Set {
-	n := make(map[interface{}]nothing)
+	n := make(map[any]nothing)
 
 	for k := range s.hash {
 		if _, exists := set.hash[k]; exists {
@@ -87,23 +76,20 @@ func (s *Set) Intersection(set *Set) *Set {
 	return &Set{n}
 }
 
-// Return the number of items in the set
 func (s *Set) Len() int {
 	return len(s.hash)
 }
 
-// Test whether or not this set is a proper subset of "set"
 func (s *Set) ProperSubsetOf(set *Set) bool {
 	return s.SubsetOf(set) && s.Len() < set.Len()
 }
 
-// Remove an element from the set
-func (s *Set) Remove(element interface{}) {
+func (s *Set) Remove(element any) {
 	delete(s.hash, element)
 }
 
 func (s *Set) Minus(set *Set) *Set {
-	n := make(map[interface{}]nothing)
+	n := make(map[any]nothing)
 	for k := range s.hash {
 		n[k] = nothing{}
 	}
@@ -115,7 +101,6 @@ func (s *Set) Minus(set *Set) *Set {
 	return &Set{n}
 }
 
-// Test whether or not this set is a subset of "set"
 func (s *Set) SubsetOf(set *Set) bool {
 	if s.Len() > set.Len() {
 		return false
@@ -125,12 +110,12 @@ func (s *Set) SubsetOf(set *Set) bool {
 			return false
 		}
 	}
+
 	return true
 }
 
-// Find the union of two sets
 func (s *Set) Union(set *Set) *Set {
-	n := make(map[interface{}]nothing)
+	n := make(map[any]nothing)
 
 	for k := range s.hash {
 		n[k] = nothing{}
@@ -142,8 +127,8 @@ func (s *Set) Union(set *Set) *Set {
 	return &Set{n}
 }
 
-func (s *Set) Values() []interface{} {
-	values := []interface{}{}
+func (s *Set) Values() []any {
+	values := []any{}
 
 	for k := range s.hash {
 		values = append(values, k)