diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..f7647a0
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,29 @@
+on: [push, pull_request]
+name: CI
+jobs:
+  build:
+    name: "Build on Racket '${{ matrix.racket-version }}' (${{ matrix.racket-variant }})"
+    runs-on: ubuntu-latest
+    continue-on-error: ${{ matrix.experimental || false }}
+    strategy:
+      fail-fast: false
+      matrix:
+        racket-version: ["stable", "current"]
+        racket-variant: ["BC", "CS"]
+        include:
+          - racket-version: current
+            experimental: true
+    steps:
+      - uses: actions/checkout@v4
+      - uses: Bogdanp/setup-racket@v1.12
+        with:
+          architecture: x64
+          distribution: full
+          variant: ${{ matrix.racket-variant }}
+          version: ${{ matrix.racket-version }}
+      - name: Installing uahgi2 and its dependencies
+        run: raco pkg install --no-docs --auto --name uahgi2
+      - name: Compiling uahgi2 and building its docs
+        run: raco setup --check-pkg-deps --unused-pkg-deps uahgi2
+      - name: Testing uahgi2
+        run: raco test -x -p uahgi2
diff --git a/expander.rkt b/expander.rkt
index 2c87707..df5ea50 100644
--- a/expander.rkt
+++ b/expander.rkt
@@ -1,6 +1,4 @@
 #lang br/quicklang
-(require syntax/parse/define)
-
 (define paperwidth #f)
 (define paperheight #f)
 (define (set x y) (set! x y))
@@ -21,14 +19,17 @@
 (define-macro-cases u-expr
   [(u-expr (u-atom ITEM)) #'ITEM]
   [(u-expr (u-converting-num (u-number NUM))) #'NUM]
-  [(u-expr X)             #'X])
+  [(u-expr X) #'X])
 
 (define-macro-cases u-sexp
     [(u-sexp (u-expr (u-atom (u-id "set"))) X Y) #'(set! X Y)]
-    [(u-sexp X Y) #'[X Y]]
+    ;[(u-sexp X Y) #'[X Y]]
     [(u-sexp REQ OPT ...)
-     #'(let ([head REQ])
-       (eval `(,head OPT ...)))]
+     #'(let ([head REQ]
+             (namespace (current-namespace)))
+        (begin
+          (println (namespace-mapped-symbols namespace))
+       ((namespace-variable-value head namespace)  OPT ...)))]
   )
 
 (define-macro (u-module-begin (u-program LINE ...))