diff --git a/CMakeLists.txt b/CMakeLists.txt
index 10ed5a2..1516e03 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,9 +17,11 @@ pkg_check_modules(NIX_MAIN REQUIRED IMPORTED_TARGET nix-main)
 add_executable(nix-irc
     src/irc/main.cpp
     src/irc/parser.cpp
+    src/irc/lexer.cpp
     src/irc/resolver.cpp
     src/irc/ir_gen.cpp
     src/irc/serializer.cpp
+    src/irc/types.cpp
 )
 
 target_include_directories(nix-irc PRIVATE
@@ -38,10 +40,12 @@ target_link_libraries(nix-irc PRIVATE
 add_library(nix-ir-plugin MODULE
     src/plugin.cpp
     src/irc/parser.cpp
+    src/irc/lexer.cpp
     src/irc/resolver.cpp
     src/irc/ir_gen.cpp
     src/irc/serializer.cpp
     src/irc/evaluator.cpp
+    src/irc/types.cpp
 )
 
 # Include directories from pkg-config
@@ -65,6 +69,10 @@ target_link_libraries(nix-ir-plugin PRIVATE
     ${NIX_MAIN_LINK_LIBRARIES}
 )
 
+# Set output directories to build/
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
+
 # Set output name
 set_target_properties(nix-ir-plugin PROPERTIES
     PREFIX ""
@@ -79,6 +87,8 @@ add_executable(regression_test
     tests/regression_test.cpp
     src/irc/serializer.cpp
     src/irc/parser.cpp
+    src/irc/lexer.cpp
+    src/irc/types.cpp
 )
 
 target_include_directories(regression_test PRIVATE
@@ -93,3 +103,7 @@ target_link_libraries(regression_test PRIVATE
     ${NIX_EXPR_LINK_LIBRARIES}
     ${NIX_UTIL_LINK_LIBRARIES}
 )
+
+# CTest integration
+enable_testing()
+add_test(NAME regression_test COMMAND regression_test)
diff --git a/flake.nix b/flake.nix
index 4f98a7f..ad043d0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -11,17 +11,19 @@
     in {
       default = pkgs.mkShell {
         name = "nixir";
-        buildInputs = with pkgs; [
+        buildInputs = with pkgs; let
+          nixForLinking = nixVersions.nixComponents_2_32;
+        in [
           boost.dev
           libblake3.dev
+          pegtl
 
-          nixVersions.nixComponents_2_32.nix-store
-          nixVersions.nixComponents_2_32.nix-expr
-          nixVersions.nixComponents_2_32.nix-cmd
-          nixVersions.nixComponents_2_32.nix-fetchers
-          nixVersions.nixComponents_2_32.nix-main
-          nixVersions.nixComponents_2_32.nix-util
-          nixVersions.nix_2_32
+          nixForLinking.nix-store
+          nixForLinking.nix-expr
+          nixForLinking.nix-cmd
+          nixForLinking.nix-fetchers
+          nixForLinking.nix-main
+          nixForLinking.nix-util
         ];
 
         nativeBuildInputs = with pkgs; [
diff --git a/tests/fixtures/lambda_pattern.nixr b/tests/fixtures/lambda_pattern.nixr
new file mode 100644
index 0000000..4e34156
Binary files /dev/null and b/tests/fixtures/lambda_pattern.nixr differ
diff --git a/tests/fixtures/string_interp.nixr b/tests/fixtures/string_interp.nixr
new file mode 100644
index 0000000..0c4d4a2
Binary files /dev/null and b/tests/fixtures/string_interp.nixr differ
diff --git a/tests/language/interp_test.nix b/tests/language/interp_test.nix
new file mode 100644
index 0000000..73b4c16
--- /dev/null
+++ b/tests/language/interp_test.nix
@@ -0,0 +1,2 @@
+# Test string interpolation
+let x = "world"; in "Hello ${x}!"
diff --git a/tests/language/pattern_test.nix b/tests/language/pattern_test.nix
new file mode 100644
index 0000000..e654f6c
--- /dev/null
+++ b/tests/language/pattern_test.nix
@@ -0,0 +1,5 @@
+# Test lambda patterns
+({
+  name,
+  version ? "1.0",
+}: "${name}-${version}") {name = "test";}