diff --git a/src/interpreter.ts b/src/interpreter.ts
index ea319ec..684c4d8 100644
--- a/src/interpreter.ts
+++ b/src/interpreter.ts
@@ -65,7 +65,7 @@ export function evaluate(ast: AST, env: Env): Value {
             return {
                 kind: 'constructor',
                 name: ast.name,
-                args: [] // TODO: constructors args
+                args: []
             };
 
         case 'let': {
@@ -105,6 +105,16 @@ export function evaluate(ast: AST, env: Env): Value {
 
             const func = evaluate(ast.func, env);
 
+            // Constructor application
+            if (func.kind === 'constructor') {
+                const argValues = ast.args.map(arg => evaluate(arg, env));
+                return {
+                    kind: 'constructor',
+                    name: func.name,
+                    args: [...func.args, ...argValues]
+                };
+            }
+
             if (func.kind !== 'closure')
                 throw new Error('Not a function');
 
diff --git a/src/main.ts b/src/main.ts
index b94d137..1904586 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -37,3 +37,11 @@ e(`factorial = n \\ n
   | n \\ n * factorial (n - 1);
 
   factorial 5`)
+
+e(`factorial = n \\ n
+  | 0 \\ 1
+  | n \\ n * factorial (n - 1);
+
+  factorial 5`)
+
+e('some5 = Some 5; some5');