feat: add Try() func to deal with Result type

Author: initdc

Rakefile

@@ -19,3 +19,7 @@ end
 task :test_option do
   sh "go test -cover -v ./option"
 end
+
+task :main do
+  sh "go run main.go"
+end

e2e_test.go renamed to e2e/e2e_test.go

@@ -2,9 +2,10 @@ package e2e_test
 
 import (
 	"fmt"
+	"testing"
+
 	. "github.com/initdc/types/option"
 	. "github.com/initdc/types/result"
-	"testing"
 )
 
 func TestE2E(t *testing.T) {
@@ -16,7 +17,6 @@ func TestE2E(t *testing.T) {
 
 	n1 := None[int]()
 
-
 	// Result
 	var r1 Result[int, string]
 	r1.Ok(1)

main.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	. "github.com/initdc/types/result"
+)
+
+func Div(a, b int) Result[int, rune] {
+	if b == 0 {
+		return Err[int]('E')
+	}
+	return Ok[int, rune](a / b)
+}
+
+func closure(r rune) Result[float32, string] {
+	goto clean
+
+clean:
+	err := Err[float32](string(r))
+	fmt.Printf("%#v\n", err)
+	os.Exit(255)
+	return err
+}
+
+func main() {
+	f1 := func(x int) float32 { return float32(x) * 2 }
+
+	r := Div(10, 0)
+	fmt.Printf("%#v\n", Try(r, f1, closure))
+
+	e := Div(10, 2)
+	fmt.Printf("%#v\n", Try(e, f1, closure))
+}

result/result.go

@@ -46,11 +46,11 @@ func (r *Result[T, E]) Err(e E) {
 }
 
 func (r Result[T, E]) Valid() bool {
-  return r.ok
+	return r.ok
 }
 
 func (r Result[T, E]) Assigned() bool {
-  return r.assigned
+	return r.assigned
 }
 
 func (r Result[T, E]) IsOk() bool {
@@ -189,6 +189,15 @@ func OrElse[T, E, F any](r Result[T, E], op func(E) Result[T, F]) Result[T, F] {
 	return op(r.err)
 }
 
+func Try[T, E, U, F any](r Result[T, E], op func(T) U, closure func(E) Result[U, F]) Result[U, F] {
+	if r.ok {
+		return Ok[U, F](op(r.value))
+	}
+	closure(r.err)
+	// unreachable
+	return closure(r.err)
+}
+
 func (r Result[T, E]) UnwrapOr(def T) T {
 	if r.ok {
 		return r.value

result/result_test.go

@@ -3,15 +3,16 @@ package result
 import (
 	"errors"
 	"fmt"
-	"github.com/stretchr/testify/assert"
 	"strconv"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestOk(t *testing.T) {
 	var a = Result[int, string]{
-		value: 1,
-		ok: true,
+		value:    1,
+		ok:       true,
 		assigned: true,
 	}
 
@@ -27,8 +28,8 @@ func TestOk(t *testing.T) {
 
 func TestErr(t *testing.T) {
 	var a = Result[int, string]{
-		err: "error",
-		ok: false,
+		err:      "error",
+		ok:       false,
 		assigned: true,
 	}
 
@@ -266,6 +267,17 @@ func TestOrElse(t *testing.T) {
 	assert.Equal(t, OrElse(OrElse(e, err), err), Err[int, int](3))
 }
 
+func TestTry(t *testing.T) {
+	f1 := func(x int) float32 { return float32(x) * 2 }
+	closure := func(e rune) Result[float32, string] { return Err[float32, string](string(e)) }
+
+	r := Ok[int, rune](1)
+	assert.Equal(t, Try(r, f1, closure), Ok[float32, string](2.0))
+
+	e := Err[int, rune]('E')
+	assert.Equal(t, Try(e, f1, closure), Err[float32, string]("E"))
+}
+
 func TestUnwrapOr(t *testing.T) {
 	r := Ok[int, string](9)
 	assert.Equal(t, r.UnwrapOr(2), 9)