diff --git a/src/haz3lcore/statics/TermBase.re b/src/haz3lcore/statics/TermBase.re
index 5c3a1d8aee..b74d9dacda 100644
--- a/src/haz3lcore/statics/TermBase.re
+++ b/src/haz3lcore/statics/TermBase.re
@@ -147,6 +147,8 @@ and UExp: {
   let int_op_to_string: op_bin_int => string;
   let float_op_to_string: op_bin_float => string;
   let string_op_to_string: op_bin_string => string;
+  let bin_op_to_string: op_bin => string;
+  let un_op_to_string: op_un => string;
 } = {
   [@deriving (show({with_path: false}), sexp, yojson)]
   type op_un_bool =
diff --git a/src/haz3lweb/SexpConversion.re b/src/haz3lweb/SexpConversion.re
new file mode 100644
index 0000000000..548cec740d
--- /dev/null
+++ b/src/haz3lweb/SexpConversion.re
@@ -0,0 +1,155 @@
+open Haz3lcore;
+open Sexplib;
+
+let rec go: Term.UExp.t => Sexp.t =
+  term => {
+    switch (term.term) {
+    | Invalid(string) => Atom(string)
+    | EmptyHole => Atom("?")
+    | MultiHole(_) => Atom("Not implemented")
+    | Triv => List([])
+    | Bool(bool) => Atom(string_of_bool(bool))
+    | Int(int) => Atom(string_of_int(int))
+    | Float(float) => Atom(string_of_float(float))
+    | String(string) => Atom("\"" ++ string ++ "\"")
+    | ListLit(list) => List([Sexp.Atom("list")] @ List.map(go, list))
+    | Parens(exp) => go(exp)
+    | Constructor(string) => Atom(string)
+    | Fun(pat, exp) => List([Atom("fun"), goUPat(pat), go(exp)])
+    | Tuple(list) => List([Sexp.Atom("tuple")] @ List.map(go, list))
+    | Var(t) => Atom(t)
+    | Let(pat, exp1, exp2) =>
+      List([Atom("let"), List([go(exp1), go(exp2)]), goUPat(pat)])
+    | TyAlias(pat, typ, exp) =>
+      List([Atom("type"), goUTPat(pat), goTyp(typ), go(exp)])
+    | Ap(func, arg) => List([go(func), go(arg)])
+    | If(cond, thenBranch, elseBranch) =>
+      List([Atom("if"), go(cond), go(thenBranch), go(elseBranch)])
+    | Seq(exp1, exp2) => List([Atom("seq"), go(exp1), go(exp2)])
+    | Test(t) => List([Atom("test"), go(t)])
+    | Cons(head, tail) => List([Atom("cons"), go(head), go(tail)])
+    | ListConcat(list1, list2) => List([Atom("@"), go(list1), go(list2)])
+    | UnOp(op_un, a) =>
+      List([Atom(TermBase.UExp.un_op_to_string(op_un)), go(a)])
+    | BinOp(op_bin, a, b) =>
+      List([Atom(TermBase.UExp.bin_op_to_string(op_bin)), go(a), go(b)])
+    | Match(exp, cases) =>
+      List([Atom("case"), go(exp), List(List.map(goRule, cases))])
+    };
+  }
+
+and goRule: ((Term.UPat.t, Term.UExp.t)) => Sexp.t = {
+  ((pat, exp)) => List([goUPat(pat), go(exp)]);
+}
+
+and goUPat: Term.UPat.t => Sexp.t =
+  pat => {
+    switch (pat.term) {
+    | EmptyHole => Atom("?")
+    | Triv => List([])
+    | MultiHole(_) => Atom("Not implemented")
+    | Int(x) => Atom(string_of_int(x))
+    | Float(x) => Atom(string_of_float(x))
+    | Bool(x) => Atom(string_of_bool(x))
+    | String(x) => Atom("\"" ++ x ++ "\"")
+    | ListLit(list) => List([Sexp.Atom("list")] @ List.map(goUPat, list))
+    | Cons(head, tail) =>
+      List([Sexp.Atom("cons"), goUPat(head), goUPat(tail)])
+    | Parens(pat) => goUPat(pat)
+    | Ap(pat1, pat2) => List([goUPat(pat1), goUPat(pat2)])
+    | Invalid(string) => Atom(string)
+    | Var(t) => Atom(t)
+    | Constructor(string) => Atom(string)
+    | Tuple(list) => List([Sexp.Atom("tuple")] @ List.map(goUPat, list))
+    | Wild => Atom("_")
+    | TypeAnn(pat, typ) => List([goUPat(pat), goTyp(typ)])
+    };
+  }
+
+// Only for type declarations!
+and goUTPat: Term.UTPat.t => Sexp.t =
+  pat => {
+    switch (pat.term) {
+    | EmptyHole => Atom("?")
+    | MultiHole(_) => Atom("Not implemented")
+    | Invalid(string) => Atom(string)
+    | Var(string) => Atom(string)
+    };
+  }
+
+and goTyp: Term.UTyp.t => Sexp.t =
+  typ => {
+    switch (typ.term) {
+    | EmptyHole => Atom("EmptyHole")
+    | MultiHole(_) => Atom("MultiHole")
+    | Int => Atom("Int")
+    | Float => Atom("Float")
+    | Bool => Atom("Bool")
+    | String => Atom("String")
+    | List(t) => List([Sexp.Atom("list"), goTyp(t)])
+    //Atom("[" ++ Sexp.to_string_mach(goTyp(t)) ++ "]")
+    | Tuple(list) => List([Sexp.Atom("tuple")] @ List.map(goTyp, list))
+    | Var(string) => Atom(string)
+    | Constructor(string) => Atom(string)
+    | Invalid(string) => Atom(string)
+    | Sum(_list) => Atom("list") //List([Sexp.Atom("sum")] @ List.map(goTyp, list))
+    | Arrow(_, _) => Atom("Arrow")
+    | Parens(_) => Atom("Parens")
+    | Ap(_, _) => Atom("Ap")
+    };
+  };
+
+// Inverse of go
+let rec sexp_of_uexp: Sexplib.Sexp.t => string =
+  sexp => {
+    switch (sexp) {
+    | Atom(string) => string
+    | List([Atom("fun"), pat, exp]) =>
+      "fun " ++ sexp_of_uexp(pat) ++ " -> " ++ sexp_of_uexp(exp)
+    | List([Atom("case"), exp, List(cases)]) =>
+      "case "
+      ++ sexp_of_uexp(exp)
+      ++ "\n"
+      ++ String.concat("\n", List.map(rule_to_string, cases))
+      ++ "\nend"
+    | List([Atom("let"), List([exp1, exp2]), pat]) =>
+      "let "
+      ++ sexp_of_uexp(pat)
+      ++ " = "
+      ++ sexp_of_uexp(exp1)
+      ++ " in "
+      ++ sexp_of_uexp(exp2)
+    | List([Atom("type"), pat, typ, exp]) =>
+      "type "
+      ++ sexp_of_uexp(pat)
+      ++ " = "
+      ++ sexp_of_uexp(typ)
+      ++ " in "
+      ++ sexp_of_uexp(exp)
+    | List([Atom("if"), cond, thenBranch, elseBranch]) =>
+      "if "
+      ++ sexp_of_uexp(cond)
+      ++ " then "
+      ++ sexp_of_uexp(thenBranch)
+      ++ " else "
+      ++ sexp_of_uexp(elseBranch)
+    | List([Atom("seq"), exp1, exp2]) =>
+      sexp_of_uexp(exp1) ++ "; " ++ sexp_of_uexp(exp2)
+    | List([Atom("test"), t]) => "test " ++ sexp_of_uexp(t)
+    | List([Atom("cons"), head, tail]) =>
+      sexp_of_uexp(head) ++ " :: " ++ sexp_of_uexp(tail)
+    | List([Atom("@"), list1, list2]) =>
+      sexp_of_uexp(list1) ++ " @ " ++ sexp_of_uexp(list2)
+    | List(list) =>
+      "(" ++ String.concat(" ", List.map(sexp_of_uexp, list)) ++ ")"
+    };
+  }
+
+and rule_to_string: Sexplib.Sexp.t => string =
+  sexp => {
+    switch (sexp) {
+    | List([pat, exp]) =>
+      " | " ++ sexp_of_uexp(pat) ++ " => " ++ sexp_of_uexp(exp)
+    | _ => failwith("expected rule")
+    };
+  };
diff --git a/src/haz3lweb/Update.re b/src/haz3lweb/Update.re
index 804682c202..f2fa2093b8 100644
--- a/src/haz3lweb/Update.re
+++ b/src/haz3lweb/Update.re
@@ -172,6 +172,7 @@ let reevaluate_post_update = (settings: Settings.t) =>
   | DebugAction(_)
   | DoTheThing
   | StoreKey(_)
+  | PrintSexp
   | ExportPersistentData => false
   | MUVSyntax(_)
   | Benchmark(_)
@@ -312,6 +313,19 @@ let rec apply =
         : Result.t(Model.t) => {
   let m: Result.t(Model.t) =
     switch (update) {
+    | PrintSexp =>
+      let editor = model.editors |> Editors.get_editor;
+      // let str = Printer.to_string_selection(editor);
+      let zipper = Editor.get_z(editor);
+      let sel = zipper.selection.content;
+      let term = MakeTerm.go(sel) |> fst;
+      let sexp = SexpConversion.go(term);
+      let str = Sexplib.Sexp.to_string_hum(sexp);
+      let alt_str = SexpConversion.sexp_of_uexp(sexp);
+
+      print_endline("PrintSexp: " ++ str);
+      print_endline("PrintSexp (alt): " ++ alt_str);
+      Ok(model);
     | Reset => Ok(Model.reset(model))
     | Set(s_action) =>
       let model = update_settings(s_action, model);
diff --git a/src/haz3lweb/UpdateAction.re b/src/haz3lweb/UpdateAction.re
index e4d75479ea..d1a50268a5 100644
--- a/src/haz3lweb/UpdateAction.re
+++ b/src/haz3lweb/UpdateAction.re
@@ -62,6 +62,7 @@ type benchmark_action =
 [@deriving (show({with_path: false}), sexp, yojson)]
 type t =
   /* meta */
+  | PrintSexp
   | Reset
   | Set(settings_action)
   | SetMeta(set_meta)
diff --git a/src/haz3lweb/view/LangDoc.re b/src/haz3lweb/view/LangDoc.re
index c42a0a1643..4fd708998c 100644
--- a/src/haz3lweb/view/LangDoc.re
+++ b/src/haz3lweb/view/LangDoc.re
@@ -2927,6 +2927,7 @@ let view =
             explanation,
           ),
           section(~section_clss="examples", ~title="Examples", example),
+          section(~section_clss="sexp-test", ~title="sexp test", example),
         ],
       ),
     ],
diff --git a/src/haz3lweb/view/ScratchMode.re b/src/haz3lweb/view/ScratchMode.re
index 2bcc7626c4..f32ce7130d 100644
--- a/src/haz3lweb/view/ScratchMode.re
+++ b/src/haz3lweb/view/ScratchMode.re
@@ -89,6 +89,10 @@ let download_slide_state = state => {
   JsUtil.download_json("hazel-scratchpad", json_data);
 };
 
+let get_sexp = _state => {
+  print_endline("get_sexp");
+};
+
 let toolbar_buttons = (~inject, state: ScratchSlide.state) => {
   let export_button =
     Widgets.button(
@@ -99,6 +103,12 @@ let toolbar_buttons = (~inject, state: ScratchSlide.state) => {
       },
       ~tooltip="Export Scratchpad",
     );
+  let debug_button =
+    Widgets.button(
+      Icons.eye,
+      _ => {inject(UpdateAction.PrintSexp)},
+      ~tooltip="Debug",
+    );
   let import_button =
     Widgets.file_select_button(
       "import-scratchpad",
@@ -128,5 +138,5 @@ let toolbar_buttons = (~inject, state: ScratchSlide.state) => {
       },
       ~tooltip="Reset Scratchpad",
     );
-  [export_button, import_button] @ [reset_button];
+  [export_button, import_button, debug_button] @ [reset_button];
 };