diff --git a/pkg/lambda/expression.go b/pkg/lambda/expression.go
index d9678d2..affaf54 100644
--- a/pkg/lambda/expression.go
+++ b/pkg/lambda/expression.go
@@ -1,13 +1,11 @@
 package lambda
 
-// Expression represents an immutable lambda calculus expression.
 type Expression interface {
 	Accept(Visitor)
 }
 
 /** ------------------------------------------------------------------------- */
 
-// Abstraction represents a lambda abstraction (λx. body).
 type Abstraction struct {
 	parameter string
 	body      Expression
@@ -31,7 +29,6 @@ func NewAbstraction(parameter string, body Expression) *Abstraction {
 
 /** ------------------------------------------------------------------------- */
 
-// Application represents function application (f arg).
 type Application struct {
 	function Expression
 	argument Expression
@@ -55,7 +52,6 @@ func NewApplication(function Expression, argument Expression) *Application {
 
 /** ------------------------------------------------------------------------- */
 
-// Variable represents a variable reference.
 type Variable struct {
 	value string
 }
diff --git a/pkg/lambda/rename.go b/pkg/lambda/rename.go
index 3a1d687..7a52796 100644
--- a/pkg/lambda/rename.go
+++ b/pkg/lambda/rename.go
@@ -1,6 +1,5 @@
 package lambda
 
-// Rename replaces all occurrences of target variable with newName.
 func Rename(expr Expression, target string, newName string) Expression {
 	switch e := expr.(type) {
 	case *Variable:
diff --git a/pkg/lambda/substitute.go b/pkg/lambda/substitute.go
index d2bb3d9..b89f8e0 100644
--- a/pkg/lambda/substitute.go
+++ b/pkg/lambda/substitute.go
@@ -1,6 +1,5 @@
 package lambda
 
-// Substitute replaces all free occurrences of target with replacement.
 func Substitute(expr Expression, target string, replacement Expression) Expression {
 	switch e := expr.(type) {
 	case *Variable: