integrate maybe (#7)

Co-authored-by: Gennaro Del Sorbo <gdelsorbo@newrelic.com>

README.md

@@ -15,24 +15,32 @@ result, err := patternmatch.ResultMatch[int, string](70).
 // Result will be "> 50", nil
 
 result, err := patternmatch.ResultMatch[int, string](2).
-        When(func(x int) bool { return x > 100 }, func() string { return "> 100" }).
-        When(func(x int) bool { return x > 50 }, func() string { return "> 50" }).
-        When(func(x int) bool { return x > 10 }, func() string { return "> 10" }).
-        Result()
+    When(func(x int) bool { return x > 100 }, func() string { return "> 100" }).
+    When(func(x int) bool { return x > 50 }, func() string { return "> 50" }).
+    When(func(x int) bool { return x > 10 }, func() string { return "> 10" }).
+    Result()
 
 // result will be "", error{"pattern not matched"}
 
+maybeResult := patternmatch.ResultMatch[int, string](11).
+    When(func(x int) bool { return x > 100 }, func() string { return "> 100" }).
+    When(func(x int) bool { return x > 50 }, func() string { return "> 50" }).
+    When(func(x int) bool { return x > 10 }, func() string { return "> 10" }).
+    MaybeResult()
+
+// result will be Optional[string], error{"pattern not matched"}
+
 ```
 
 Using defaults:
 
 ```go
 
 result, err := patternmatch.ResultMatch[int, string](2).
-        When(func(x int) bool { return x.(int) > 100 }, func() string { return "> 100" }).
-        When(func(x int) bool { return x.(int) > 50 }, func() string { return "> 50" }).
-        When(func(x int) bool { return x.(int) > 10 }, func() string { return "> 10" }).
-        ResultOrDefault("< 10")
+    When(func(x int) bool { return x.(int) > 100 }, func() string { return "> 100" }).
+    When(func(x int) bool { return x.(int) > 50 }, func() string { return "> 50" }).
+    When(func(x int) bool { return x.(int) > 10 }, func() string { return "> 10" }).
+    ResultOrDefault("< 10")
 
 // Result will be "< 10", nil
 
@@ -42,10 +50,10 @@ Non-conditional pattern matching:
 
 ```go
 result, err := patternmatch.ResultMatch[interface{}, string](5).
-        WhenValue(5, func() string { return "is int 5" }).
-        WhenValue("10", func() string { return "is string 10" }).
-        WhenValue(true, func() string { return "is bool" }).
-        Result()
+    WhenValue(5, func() string { return "is int 5" }).
+    WhenValue("10", func() string { return "is string 10" }).
+    WhenValue(true, func() string { return "is bool" }).
+    Result()
 
 // Result will be "is int 5", nil
 ```

go.mod

@@ -1,4 +1,4 @@
-module gopatternmatching
+module github.com/jd78/gopatternmatching
 
 go 1.21
 
@@ -9,6 +9,7 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/jd78/go-optional v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -2,6 +2,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/jd78/go-optional v1.0.1 h1:sbss/rnM6dYO4rFohLAK80v+S8SGKwqbany9Mjdz7Xw=
+github.com/jd78/go-optional v1.0.1/go.mod h1:7rD8V+s0NomoZ+X13XTmlBpNERPP/exRr7hqHpCle14=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=

pattern.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 
 	"github.com/google/go-cmp/cmp"
+	gooptional "github.com/jd78/go-optional"
 )
 
 type match[T any] struct {
@@ -95,7 +96,7 @@ func (m matchResult[T, K]) WhenValue(val T, a func() K) matchResult[T, K] {
 	return m
 }
 
-// Get the result from the pattern or throws if not matched
+// Get the result from the pattern
 func (m matchResult[T, K]) Result() (K, error) {
 	var zeroK K
 	if cmp.Equal(m.output, zeroK) {
@@ -104,6 +105,15 @@ func (m matchResult[T, K]) Result() (K, error) {
 	return m.output, nil
 }
 
+// Get the optional result from the pattern or throws if not matched
+func (m matchResult[T, K]) MaybeResult() gooptional.Optional[K] {
+	var zeroK K
+	if cmp.Equal(m.output, zeroK) {
+		return gooptional.Error[K](errors.New("pattern not matched"))
+	}
+	return gooptional.Some[K](m.output)
+}
+
 // Get the result from the pattern or the passed default value
 func (m matchResult[T, K]) ResultOrDefault(def K) K {
 	var zeroK K

pattern_test.go

@@ -1,7 +1,6 @@
 package patternmatch
 
 import (
-	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -83,8 +82,12 @@ func TestIsMatched(t *testing.T) {
 	assert.True(t, b)
 }
 
-func TestT(t *testing.T) {
-	Match(5).
-		WhenValue(5, func() { fmt.Println("is 5") }).
-		WhenValue(6, func() { fmt.Println("is 6") })
+func TestMaybe(t *testing.T) {
+	maybeOpt := ResultMatch[int, string](0).
+		WhenValue(5, func() string { return "5" }).
+		WhenValue(0, func() string { return "is 0" }).
+		MaybeResult()
+
+	assert.True(t, maybeOpt.IsSome())
+	assert.Equal(t, "is 0", maybeOpt.Get())
 }