[2024] Try out Go generics

Author: kfarnung

2024/day01/main.go

@@ -17,12 +17,12 @@ func part1(input string) int64 {
 		log.Fatal(err)
 	}
 
-	lib.SortSliceInt64(first)
-	lib.SortSliceInt64(second)
+	lib.SortSliceAscending(first)
+	lib.SortSliceAscending(second)
 
 	sum := int64(0)
 	for i := 0; i < len(first); i++ {
-		sum += lib.AbsInt64(first[i] - second[i])
+		sum += lib.Abs(first[i] - second[i])
 	}
 
 	return sum
@@ -59,12 +59,12 @@ func parseInput(input string) ([]int64, []int64, error) {
 			continue
 		}
 
-		firstValue, err := lib.ParseInt64(matches[1])
+		firstValue, err := lib.ParseInt[int64](matches[1])
 		if err != nil {
 			return nil, nil, err
 		}
 
-		secondValue, err := lib.ParseInt64(matches[2])
+		secondValue, err := lib.ParseInt[int64](matches[2])
 		if err != nil {
 			return nil, nil, err
 		}

2024/go.mod

@@ -2,7 +2,10 @@ module github.com/kfarnung/advent-of-code/2024
 
 go 1.23
 
-require github.com/stretchr/testify v1.10.0
+require (
+	github.com/stretchr/testify v1.10.0
+	golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f
+)
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect

2024/go.sum

@@ -4,6 +4,8 @@ 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/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f h1:XdNn9LlyWAhLVp6P/i8QYBW+hlyhrhei9uErw2B5GJo=
+golang.org/x/exp v0.0.0-20241108190413-2d47ceb2692f/go.mod h1:D5SMRVC3C2/4+F/DB1wZsLRnSNimn2Sp/NPsCrsv8ak=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

2024/lib/intmath.go

@@ -1,16 +1,18 @@
 package lib
 
-// AbsInt64 calculates the absolute value of a given int
-func AbsInt64(n int64) int64 {
+import "golang.org/x/exp/constraints"
+
+// Abs calculates the absolute value of a given int
+func Abs[T constraints.Signed](n T) T {
 	if n < 0 {
 		return -n
 	}
 
 	return n
 }
 
-// ModInt64 calculates the modulus value (as opposed to the remainder)
+// Mod calculates the modulus value (as opposed to the remainder)
 // https://github.com/golang/go/issues/448
-func ModInt64(x, y int64) int64 {
+func Mod[T constraints.Signed](x, y T) T {
 	return ((x % y) + y) % y
 }

2024/lib/parse.go

@@ -1,18 +1,19 @@
 package lib
 
-import "strconv"
+import (
+	"strconv"
+	"unsafe"
 
-// ParseInt32 parses the string as a base-10 int
-func ParseInt32(text string) (int32, error) {
-	value, err := strconv.ParseInt(text, 10, 32)
+	"golang.org/x/exp/constraints"
+)
+
+// ParseInt64 parses the string as a base-10 int64
+func ParseInt[T constraints.Signed](text string) (T, error) {
+	size := unsafe.Sizeof(T(0))
+	value, err := strconv.ParseInt(text, 10, int(size*8))
 	if err != nil {
 		return 0, err
 	}
 
-	return int32(value), nil
-}
-
-// ParseInt64 parses the string as a base-10 int64
-func ParseInt64(text string) (int64, error) {
-	return strconv.ParseInt(text, 10, 64)
+	return T(value), nil
 }

2024/lib/point2d.go

@@ -41,7 +41,7 @@ func (p *Point2D) Rotate90DegreesCounterClockwise(count int) {
 
 // ManhattanDistance calculates the manhattan distance between two points
 func (p Point2D) ManhattanDistance(other Point2D) int64 {
-	return AbsInt64(other.X-p.X) + AbsInt64(other.Y-p.Y)
+	return Abs(other.X-p.X) + Abs(other.Y-p.Y)
 }
 
 func (p Point2D) String() string {

2024/lib/slice.go

@@ -1,12 +1,15 @@
 package lib
 
-import "sort"
+import (
+	"cmp"
+	"sort"
+)
 
 // StringSliceToInt64 converts the slice of strings to a slice of int64 values.
 func StringSliceToInt64(input []string) ([]int64, error) {
 	result := make([]int64, len(input))
 	for i, val := range input {
-		num, err := ParseInt64(val)
+		num, err := ParseInt[int64](val)
 		if err != nil {
 			return nil, err
 		}
@@ -21,7 +24,7 @@ func StringSliceToInt64(input []string) ([]int64, error) {
 func StringSliceToInt32(input []string) ([]int32, error) {
 	result := make([]int32, len(input))
 	for i, val := range input {
-		num, err := ParseInt32(val)
+		num, err := ParseInt[int32](val)
 		if err != nil {
 			return nil, err
 		}
@@ -32,7 +35,7 @@ func StringSliceToInt32(input []string) ([]int32, error) {
 	return result, nil
 }
 
-func SortSliceInt64(input []int64) {
+func SortSliceAscending[T cmp.Ordered](input []T) {
 	sort.Slice(input, func(i, j int) bool {
 		return input[i] < input[j]
 	})