diff --git a/include/serene/jit/halley.h b/include/serene/jit/halley.h
index 828106b..326a9d7 100644
--- a/include/serene/jit/halley.h
+++ b/include/serene/jit/halley.h
@@ -27,6 +27,7 @@
 #include "serene/errors.h"
 #include "serene/errors/error.h"
 #include "serene/export.h"
+#include "serene/namespace.h"
 #include "serene/utils.h"
 
 #include <llvm/ADT/StringRef.h>
@@ -181,6 +182,8 @@ public:
   llvm::Optional<errors::ErrorTree> addNS(Namespace &ns,
                                           reader::LocationRange &loc);
 
+  llvm::Optional<errors::ErrorTree> addAST(exprs::Ast &ast);
+
   Namespace &getActiveNS();
 };
 
diff --git a/include/serene/namespace.h b/include/serene/namespace.h
index 9355826..146f85b 100644
--- a/include/serene/namespace.h
+++ b/include/serene/namespace.h
@@ -147,7 +147,6 @@ public:
 
   SereneContext &getContext();
 
-  // TODO: Fix the return type and use a `llvm::Optional` instead
   /// Generate and return a MLIR ModuleOp tha contains the IR of the namespace
   /// with respect to the compilation phase
   MaybeModuleOp generate(unsigned offset = 0);
diff --git a/include/serene/slir/CMakeLists.txt b/include/serene/slir/CMakeLists.txt
index 2d751f2..08e7cf2 100644
--- a/include/serene/slir/CMakeLists.txt
+++ b/include/serene/slir/CMakeLists.txt
@@ -1,6 +1,8 @@
 set(LLVM_TARGET_DEFINITIONS dialect.td)
 mlir_tablegen(ops.h.inc -gen-op-decls)
 mlir_tablegen(ops.cpp.inc -gen-op-defs)
+mlir_tablegen(types.h.inc -gen-typedef-decls)
+mlir_tablegen(types.cpp.inc -gen-typedef-defs)
 mlir_tablegen(dialect.h.inc -gen-dialect-decls)
 mlir_tablegen(dialect.cpp.inc -gen-dialect-defs)
 add_public_tablegen_target(SereneDialectGen)
diff --git a/src/libserene/jit/halley.cpp b/src/libserene/jit/halley.cpp
index 4db14dc..b2c3bc6 100644
--- a/src/libserene/jit/halley.cpp
+++ b/src/libserene/jit/halley.cpp
@@ -462,6 +462,26 @@ MaybeJIT Halley::make(SereneContext &serene_ctx,
   return MaybeJIT(std::move(jitEngine));
 };
 
+llvm::Optional<errors::ErrorTree> Halley::addAST(exprs::Ast &ast) {
+  auto offset = activeNS->getTree().size();
+  auto errs   = activeNS->addTree(ast);
+
+  if (errs) {
+    return errs.getValue();
+  }
+
+  auto maybeModule = activeNS->compileToLLVMFromOffset(offset);
+
+  auto tsm = std::move(maybeModule.getValue());
+  tsm.withModuleDo([](llvm::Module &m) { packFunctionArguments(&m); });
+
+  auto *dylib = ctx.getLatestJITDylib(*activeNS);
+  // TODO: Make sure that the data layout of the module is the same as the
+  // engine
+  cantFail(engine->addIRModule(*dylib, std::move(tsm)));
+  return llvm::None;
+};
+
 Namespace &Halley::getActiveNS() { return *activeNS; };
 
 llvm::Expected<std::unique_ptr<Halley>> makeHalleyJIT(SereneContext &ctx) {
diff --git a/src/libserene/serene.cpp b/src/libserene/serene.cpp
index 0e8ac26..be977c2 100644
--- a/src/libserene/serene.cpp
+++ b/src/libserene/serene.cpp
@@ -109,34 +109,37 @@ SERENE_EXPORT exprs::MaybeAst read(SereneContext &ctx, std::string &input) {
 
 SERENE_EXPORT exprs::MaybeNode eval(SereneContext &ctx, exprs::Ast &input) {
 
-  // TODO: Fix the eval function
-  UNUSED(input);
-
   auto loc = reader::LocationRange::UnknownLocation("nsname");
 
-  auto ns = ctx.importNamespace("docs.examples.hello_world", loc);
+  // auto ns = ctx.importNamespace("docs.examples.hello_world", loc);
 
-  if (!ns) {
-    auto es        = ns.getError();
-    auto nsloadErr = errors::makeError(loc, errors::NSLoadError);
-    es.push_back(nsloadErr);
-    return exprs::MaybeNode::error(es);
+  // if (!ns) {
+  //   auto es        = ns.getError();
+  //   auto nsloadErr = errors::makeError(loc, errors::NSLoadError);
+  //   es.push_back(nsloadErr);
+  //   return exprs::MaybeNode::error(es);
+  // }
+
+  auto errs = ctx.jit->addAST(input);
+  if (errs) {
+    return exprs::MaybeNode::error(errs.getValue());
   }
 
-  auto e    = input[0];
-  auto *sym = llvm::dyn_cast<exprs::Symbol>(e.get());
+  //   auto e    = input[0];
+  // auto *sym = llvm::dyn_cast<exprs::Symbol>(e.get());
 
-  if (sym == nullptr) {
-    return exprs::makeErrorNode(e->location, errors::UnknownError, "only sym");
-  }
+  // if (sym == nullptr) {
+  //   return exprs::makeErrorNode(e->location, errors::UnknownError, "only
+  //   sym");
+  // }
 
-  llvm::outs() << "Read: " << sym->toString() << "\n";
+  // llvm::outs() << "Read: " << sym->toString() << "\n";
 
-  // Get the anonymous expression's JITSymbol.
-  auto symptr = ctx.jit->lookup(*sym);
-  if (!symptr) {
-    return exprs::MaybeNode::error(symptr.getError());
-  }
+  // // Get the anonymous expression's JITSymbol.
+  // auto symptr = ctx.jit->lookup(*sym);
+  // if (!symptr) {
+  //   return exprs::MaybeNode::error(symptr.getError());
+  // }
 
   llvm::outs() << "eval here\n";