Merge pull request #43 from taman9333/do-notation

Do notation

do.go

@@ -0,0 +1,22 @@
+package mo
+
+import (
+	"errors"
+	"fmt"
+)
+
+// Do executes a function within a monadic context, capturing any errors that occur.
+// If the function executes successfully, its result is wrapped in a successful Result.
+// If the function panics (indicating a failure), the panic is caught and converted into an error Result.
+func Do[T any](fn func() T) (result Result[T]) {
+	defer func() {
+		if r := recover(); r != nil {
+			if err, ok := r.(error); ok {
+				result = Err[T](err)
+			} else {
+				result = Err[T](errors.New(fmt.Sprint(r)))
+			}
+		}
+	}()
+	return Ok(fn())
+}

do_test.go

@@ -0,0 +1,116 @@
+package mo
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDo_Success(t *testing.T) {
+	is := assert.New(t)
+
+	result := Do(func() string {
+		return "Hello, World!"
+	})
+
+	is.False(result.IsError())
+	is.Equal("Hello, World!", result.MustGet())
+}
+
+func TestDo_Error(t *testing.T) {
+	is := assert.New(t)
+
+	result := Do(func() string {
+		panic(errors.New("something went wrong"))
+	})
+
+	is.True(result.IsError())
+	is.EqualError(result.Error(), "something went wrong")
+}
+
+func TestDo_ComplexSuccess(t *testing.T) {
+	is := assert.New(t)
+
+	validateBooking := func(params map[string]string) Result[map[string]string] {
+		if params["guest"] != "" && params["roomType"] != "" {
+			return Ok(params)
+		}
+		return Err[map[string]string](errors.New("validation failed"))
+	}
+
+	createBooking := func(guest string) Result[string] {
+		if guest != "" {
+			return Ok("Booking Created for: " + guest)
+		}
+		return Err[string](errors.New("booking creation failed"))
+	}
+
+	assignRoom := func(booking string, roomType string) Result[string] {
+		if roomType != "" {
+			return Ok("Room Assigned: " + roomType + " for " + booking)
+		}
+		return Err[string](errors.New("room assignment failed"))
+	}
+
+	bookRoom := func(params map[string]string) Result[[]string] {
+		return Do(func() []string {
+			values := validateBooking(params).MustGet()
+			booking := createBooking(values["guest"]).MustGet()
+			room := assignRoom(booking, values["roomType"]).MustGet()
+			return []string{booking, room}
+		})
+	}
+
+	params := map[string]string{
+		"guest":    "Foo Bar",
+		"roomType": "Suite",
+	}
+
+	result := bookRoom(params)
+	is.False(result.IsError())
+	is.Equal([]string{"Booking Created for: Foo Bar", "Room Assigned: Suite for Booking Created for: Foo Bar"}, result.MustGet())
+}
+
+func TestDo_ComplexError(t *testing.T) {
+	is := assert.New(t)
+
+	validateBooking := func(params map[string]string) Result[map[string]string] {
+		if params["guest"] != "" && params["roomType"] != "" {
+			return Ok(params)
+		}
+		return Err[map[string]string](errors.New("validation failed"))
+	}
+
+	createBooking := func(guest string) Result[string] {
+		if guest != "" {
+			return Ok("Booking Created for: " + guest)
+		}
+		return Err[string](errors.New("booking creation failed"))
+	}
+
+	assignRoom := func(booking string, roomType string) Result[string] {
+		if roomType != "" {
+			return Ok("Room Assigned: " + roomType + " for " + booking)
+		}
+		return Err[string](errors.New("room assignment failed"))
+	}
+
+	bookRoom := func(params map[string]string) Result[[]string] {
+		return Do(func() []string {
+			values := validateBooking(params).MustGet()
+			booking := createBooking(values["guest"]).MustGet()
+			room := assignRoom(booking, values["roomType"]).MustGet()
+			return []string{booking, room}
+		})
+	}
+
+	params := map[string]string{
+		"guest":    "",
+		"roomType": "Suite",
+	}
+
+	result := bookRoom(params)
+	is.True(result.IsError())
+	is.EqualError(result.Error(), "validation failed")
+}