diff --git a/asl_xdsl/interpreters/asl.py b/asl_xdsl/interpreters/asl.py
index 49db157..414b4af 100644
--- a/asl_xdsl/interpreters/asl.py
+++ b/asl_xdsl/interpreters/asl.py
@@ -8,9 +8,11 @@
     TerminatorValue,
     impl,
     impl_callable,
+    impl_external,
     impl_terminator,
     register_impls,
 )
+from xdsl.ir import Operation
 
 from asl_xdsl.dialects import asl
 
@@ -32,9 +34,46 @@ def call_func(
         else:
             return interpreter.run_ssacfg_region(op.body, args, op.sym_name.data)
 
+    @impl(asl.CallOp)
+    def run_call(
+        self, interpreter: Interpreter, op: asl.CallOp, args: tuple[Any, ...]
+    ) -> tuple[Any, ...]:
+        return interpreter.call_op(op.callee.string_value(), args)
+
+    @impl(asl.AddIntOp)
+    def run_add_int(
+        self, interpreter: Interpreter, op: asl.AddIntOp, args: tuple[Any, ...]
+    ) -> tuple[Any, ...]:
+        lhs: int
+        rhs: int
+        (lhs, rhs) = args
+        return (lhs + rhs,)
+
     @impl(asl.ConstantIntOp)
     def run_constant(
         self, interpreter: Interpreter, op: asl.ConstantIntOp, args: PythonValues
     ) -> PythonValues:
         value = op.value
         return (value.data,)
+
+    # region built-in function implementations
+
+    @impl_external("asl_print_int_dec")
+    def asl_print_int_dec(
+        self, interpreter: Interpreter, op: Operation, args: PythonValues
+    ) -> PythonValues:
+        arg: int
+        (arg,) = args
+        interpreter.print(arg)
+        return ()
+
+    @impl_external("asl_print_char")
+    def asl_print_char(
+        self, interpreter: Interpreter, op: Operation, args: PythonValues
+    ) -> PythonValues:
+        arg: int
+        (arg,) = args
+        interpreter.print(chr(arg))
+        return ()
+
+    # endregion
diff --git a/asl_xdsl/tools/asl_opt.py b/asl_xdsl/tools/asl_opt.py
index f952a0c..3ede26b 100644
--- a/asl_xdsl/tools/asl_opt.py
+++ b/asl_xdsl/tools/asl_opt.py
@@ -27,7 +27,7 @@ def interpret_target(module: ModuleOp, output: IO[str]):
 
             interpreter = Interpreter(module, file=output)
             interpreter.register_implementations(ASLFunctions())
-            op = interpreter.get_op_for_symbol("main")
+            op = interpreter.get_op_for_symbol("main.0")
             trait = op.get_trait(CallableOpInterface)
             assert trait is not None
 
diff --git a/tests/filecheck/exec/exec_simple.asl b/tests/filecheck/exec/exec_simple.asl
index bd1b2e6..efad5d4 100644
--- a/tests/filecheck/exec/exec_simple.asl
+++ b/tests/filecheck/exec/exec_simple.asl
@@ -1,6 +1,6 @@
 // RUN: asl-opt --t exec %s | filecheck %s
 
-func main() => integer
+func main.0() => integer
 begin
     return 42;
 end;
diff --git a/tests/filecheck/exec/t2.mlir b/tests/filecheck/exec/t2.mlir
new file mode 100644
index 0000000..846946f
--- /dev/null
+++ b/tests/filecheck/exec/t2.mlir
@@ -0,0 +1,29 @@
+// RUN: asl-opt %s --target exec | filecheck %s
+
+// CHECK: 3
+
+asl.func @asl_print_int_dec(!asl.int)
+asl.func @asl_print_char(!asl.int)
+
+asl.func @main.0() -> !asl.int {
+    %0 = asl.constant_int 1 {attr_dict}
+    %1 = asl.constant_int 2 {attr_dict}
+    %2 = asl.call @Test.0(%0, %1) : (!asl.int, !asl.int) -> !asl.int
+    asl.call @asl_print_int_dec (%2) : (!asl.int) -> ()
+
+    asl.call @println.0() : () -> ()
+
+    %3 = asl.constant_int 0 {attr_dict}
+    asl.return %3 : !asl.int
+}
+
+asl.func @Test.0(%x : !asl.int, %y : !asl.int) -> !asl.int {
+    %0 = asl.add_int %x, %y : (!asl.int, !asl.int) -> !asl.int
+    asl.return %0 : !asl.int
+}
+
+asl.func @println.0() -> () {
+    %0 = asl.constant_int 10 {attr_dict}
+    asl.call @asl_print_char(%0) : (!asl.int) -> ()
+    asl.return
+}