made usage of first class citizen functions in go

README.md

@@ -139,3 +139,7 @@ https://the-zen-of-go.netlify.app/
 
 ### FP-Go Documentation
 https://pkg.go.dev/github.com/IBM/fp-go
+
+https://betterprogramming.pub/investigate-functional-programming-concepts-in-go-1dada09bc913
+
+https://rlee.dev/practical-guide-to-fp-ts-part-1

backend-go/internal/application/repository/helper.go

@@ -0,0 +1,14 @@
+package repository
+
+import (
+	"context"
+
+	E "github.com/IBM/fp-go/either"
+)
+
+// curried delegiert eine Methode mit Kontext und gibt eine Funktion zurück.
+func curried[T any, R any](ctx context.Context, fn func(context.Context, T) E.Either[error, R]) func(T) E.Either[error, R] {
+	return func(input T) E.Either[error, R] {
+		return fn(ctx, input)
+	}
+}

backend-go/internal/application/repository/user_repository_impl.go

@@ -1,9 +1,8 @@
 package repository
 
 import (
-	"actatempus_backend/internal/domain/entities"
-	"actatempus_backend/internal/domain/repository"
 	"actatempus_backend/internal/domain/data"
+	"actatempus_backend/internal/domain/entities"
 	"context"
 
 	E "github.com/IBM/fp-go/either"
@@ -14,37 +13,32 @@ type UserRepositoryImpl struct {
 	dataSource data.UserDataSource
 }
 
-// NewUserRepository creates a new instance of UserRepositoryImpl.
+// Create delegiert die Erstellung eines Benutzers an die Datenquelle.
-func NewUserRepository(dataSource data.UserDataSource) repository.UserRepository {
+func (r *UserRepositoryImpl) Create(ctx context.Context) func(user entities.UserCreate) E.Either[error, entities.User] {
-	return &UserRepositoryImpl{dataSource: dataSource}
+	return curried(ctx, r.dataSource.Create)
 }
 
-// Create delegates the creation of a user to the data source.
+// FindByID delegiert das Abrufen eines Benutzers nach ID an die Datenquelle.
-func (r *UserRepositoryImpl) Create(ctx context.Context, user entities.UserCreate) E.Either[error, entities.User] {
+func (r *UserRepositoryImpl) FindByID(ctx context.Context) func(id string) E.Either[error, entities.User] {
-	return r.dataSource.Create(ctx, user)
+	return curried(ctx, r.dataSource.FindByID)
 }
 
-// FindByID delegates fetching a user by ID to the data source.
+// FindByEmail delegiert das Abrufen eines Benutzers nach E-Mail an die Datenquelle.
-func (r *UserRepositoryImpl) FindByID(ctx context.Context, id string) E.Either[error, entities.User] {
+func (r *UserRepositoryImpl) FindByEmail(ctx context.Context) func(email string) E.Either[error, entities.User] {
-	return r.dataSource.FindByID(ctx, id)
+	return curried(ctx, r.dataSource.FindByEmail)
 }
 
-// FindByEmail delegates fetching a user by email to the data source.
+// Update delegiert das Aktualisieren eines Benutzers an die Datenquelle.
-func (r *UserRepositoryImpl) FindByEmail(ctx context.Context, email string) E.Either[error, entities.User] {
+func (r *UserRepositoryImpl) Update(ctx context.Context) func(user entities.UserUpdate) E.Either[error, entities.User] {
-	return r.dataSource.FindByEmail(ctx, email)
+	return curried(ctx, r.dataSource.Update)
 }
 
-// Update delegates updating a user to the data source.
+// Delete delegiert das Löschen eines Benutzers an die Datenquelle.
-func (r *UserRepositoryImpl) Update(ctx context.Context, user entities.UserUpdate) E.Either[error, entities.User] {
+func (r *UserRepositoryImpl) Delete(ctx context.Context) func(id string) E.Either[error, entities.User] {
-	return r.dataSource.Update(ctx, user)
+	return curried(ctx, r.dataSource.Delete)
 }
 
-// Delete delegates deleting a user to the data source.
+// FindAll delegiert das Abrufen aller Benutzer an die Datenquelle.
-func (r *UserRepositoryImpl) Delete(ctx context.Context, id string) E.Either[error, entities.User] {
-	return r.dataSource.Delete(ctx, id)
-}
-
-// FindAll delegates fetching all users to the data source.
 func (r *UserRepositoryImpl) FindAll(ctx context.Context) E.Either[error, []entities.User] {
 	return r.dataSource.FindAll(ctx)
 }

backend-go/internal/application/services/user_service.go

@@ -38,9 +38,9 @@ func (s *UserService) CreateUser(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
-	userCreate := mappers.MapCreateDTOToUser(userCreateDTO)
+	F.Pipe3(
-	F.Pipe2(
+		mappers.MapCreateDTOToUser(userCreateDTO),
-		s.repository.Create(c.Request.Context(), userCreate),
+		s.repository.Create(c.Request.Context()),
 		E.Map[error](mappers.MapUserToDTO),
 		E.Fold(
 			HandleError(c),
@@ -51,9 +51,9 @@ func (s *UserService) CreateUser(c *gin.Context) {
 
 // GetUserByID handles fetching a user by their ID.
 func (s *UserService) GetUserByID(c *gin.Context) {
-	id := c.Param("id")
+	F.Pipe3(
-	F.Pipe2(
+		c.Param("id"),
-		s.repository.FindByID(c.Request.Context(), id),
+		s.repository.FindByID(c.Request.Context()),
 		E.Map[error](mappers.MapUserToDTO),
 		E.Fold(
 			HandleError(c),
@@ -84,10 +84,9 @@ func (s *UserService) UpdateUser(c *gin.Context) {
 		return
 	}
 
-	userUpdate := mappers.MapUpdateDTOToUser(userUpdateDTO, id)
+	F.Pipe3(
-
+		mappers.MapUpdateDTOToUser(userUpdateDTO, id),
-	F.Pipe2(
+		s.repository.Update(c.Request.Context()),
-		s.repository.Update(c.Request.Context(), userUpdate),
 		E.Map[error](mappers.MapUserToDTO),
 		E.Fold(
 			HandleError(c),
@@ -98,15 +97,13 @@ func (s *UserService) UpdateUser(c *gin.Context) {
 
 // DeleteUser handles deleting a user by their ID.
 func (s *UserService) DeleteUser(c *gin.Context) {
-	id := c.Param("id")
+	F.Pipe3(
-
+		c.Param("id"),
-	F.Pipe2(
+		s.repository.Delete(c.Request.Context()),
-		s.repository.Delete(c.Request.Context(), id),
 		E.Map[error](mappers.MapUserToDTO),
 		E.Fold(
 			HandleError(c),
 			HandleSuccess[dto.UserDTO](c, http.StatusOK),
 		),
 	)
-
 }

backend-go/internal/domain/repository/user_repository.go

@@ -8,11 +8,12 @@ import (
 )
 
 // UserRepository defines the operations for interacting with user data.
+
 type UserRepository interface {
-	Create(ctx context.Context, user entities.UserCreate) E.Either[error,entities.User]
+	Create(ctx context.Context) func(user entities.UserCreate) E.Either[error, entities.User]
-	FindByID(ctx context.Context, id string) E.Either[error,entities.User]
+	FindByID(ctx context.Context) func(id string) E.Either[error, entities.User]
-	FindByEmail(ctx context.Context, email string) E.Either[error,entities.User]
+	FindByEmail(ctx context.Context) func(email string) E.Either[error, entities.User]
-	Update(ctx context.Context, user entities.UserUpdate) E.Either[error,entities.User]
+	Update(ctx context.Context) func(user entities.UserUpdate) E.Either[error, entities.User]
-	Delete(ctx context.Context, id string) E.Either[error,entities.User]
+	Delete(ctx context.Context) func(id string) E.Either[error, entities.User]
-	FindAll(ctx context.Context)  E.Either[error,[]entities.User]
+	FindAll(ctx context.Context) E.Either[error, []entities.User] // Keine zusätzlichen Argumente nötig
 }