diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 00000000..a1cad23b
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,47 @@
+name: Build
+
+on:
+  - push
+  - pull_request
+  - workflow_dispatch
+    
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        solver:
+          - nosundials
+        plot:
+          - nogtk
+        ocaml-version:
+          - 5.2.0
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Use OCaml ${{ matrix.ocaml-version }}
+        uses: ocaml/setup-ocaml@v2
+        with:
+          ocaml-compiler: ${{ matrix.ocaml-version }}
+        
+      - name: Install OCaml dependencies
+        run: opam install -y graphics menhir alcotest
+
+      - name: Install Sundials
+        if: matrix.solver == 'sundials'
+        run: opam depext conf-sundials
+
+      - name: Install Sundials/ML
+        if: matrix.solver == 'sundials'
+        run: opam install sundialsml
+
+      - name: Install Zelus
+        run: |
+          opam pin -y -n -k path .
+          opam install -y zelus
+
+      - name: Install Gtk
+        if: matrix.plot == 'gtk'
+        run: opam install -y zelus-gtk
diff --git a/.github/workflows/opam.yml b/.github/workflows/opam.yml
new file mode 100644
index 00000000..575f235a
--- /dev/null
+++ b/.github/workflows/opam.yml
@@ -0,0 +1,25 @@
+name: Opam
+
+on:
+  push:
+    branches:
+      - 2024
+    
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Use OCaml
+        uses: ocaml/setup-ocaml@v2
+        with:
+          ocaml-compiler: 5.2.0
+            
+      - name: Install OCaml dependencies
+        run: |
+          opam install graphics zelus
+      
+
diff --git a/src/compiler/main/compiler.ml b/src/compiler/main/compiler.ml
index c6794a41..be64eb67 100644
--- a/src/compiler/main/compiler.ml
+++ b/src/compiler/main/compiler.ml
@@ -102,7 +102,7 @@ let print_message comment =
 let do_step comment output step input = 
   print_message comment;
   let o = step input in
-  if !Misc.debug then output Format.err_formatter o;
+  if !Misc.verbose then output Format.err_formatter o;
   o
 
 let do_optional_step no_step comment output step input = 
@@ -162,6 +162,8 @@ let compile modname filename =
     let p = do_step "Mark functions calls to be inlined. See below:"
 	      Printer.program Markfunctions.program p in
 
+    let _ = Zelus.pp_program p in
+    
     (* source-to-source transformations *)
 
     (* defines the initial global environment for values *)
diff --git a/src/dune b/src/dune
index b8057a8c..7497e80b 100644
--- a/src/dune
+++ b/src/dune
@@ -214,6 +214,7 @@
   (libraries zelus.parser_lib zelus.global_lib zelus.zrun_lib
   zelus.typing_lib zelus.causality_lib zelus.initialization_lib
   zelus.rewrite_lib zelus.seqcode_lib)
+  (preprocess (pps ppx_deriving.show))
   (promote (until-clean) (into ..)))
 
 (install
diff --git a/src/global/zelus.ml b/src/global/zelus.ml
index a3fc84bf..930f7bf3 100644
--- a/src/global/zelus.ml
+++ b/src/global/zelus.ml
@@ -488,4 +488,7 @@ and ('info, 'ienv) implementation_desc =
 type ('info, 'ienv) program = 
   { p_impl_list : ('info, 'ienv) implementation list;
     p_index : Ident.num }
+    [@@deriving show]
+
+let f = show_program;;