Add complicated recursion and nesting -- fail

For recursive functions, the self-reference was considered a free
variable wrt. defunctionalization

src/Defun.ml

@@ -65,8 +65,7 @@ let rec walk_term fs t =
     | S.LetVal (var, value, next) ->
             let fs, nNext = walk_term fs next in
             fs, T.LetVal(var, value, nNext)
-    | S.LetBlo (var, S.Lam(_, vars, body), next) ->
-            (* FIXME is handling of recursive functions correct? *)
+    | S.LetBlo (var, S.Lam(self, vars, body), next) ->
             let fs, nNext = walk_term fs next in
             let fs, nBody = walk_term fs body in
             let arity = List.length vars + 1 in
@@ -77,15 +76,24 @@ let rec walk_term fs t =
                 vars
                 (S.vvars (List.tl args)) in
             let thisTag = freshTag () in
-            let freeVars = Atom.Set.elements @@
+            let freeVars =
                 Atom.Set.diff
                     (S.fv_term body)
                     (Atom.Set.of_list vars)
                 in
+            let freeVarsBranch, freeVarsCon = (match self with
+                | S.Self self ->
+                        let freeVars = Atom.Set.elements @@
+                            Atom.Set.diff freeVars
+                                (Atom.Set.singleton self) in
+                        self :: freeVars, var :: freeVars
+                | S.NoSelf ->
+                        let freeVars = Atom.Set.elements freeVars in
+                        freeVars, freeVars) in
             let thisFunc =
-                T.Branch(thisTag, freeVars, nBody) in
+                T.Branch(thisTag, freeVarsBranch, nBody) in
             let fs = add_func fs arity thisFunc in
-            fs, T.LetBlo (var, T.Con(thisTag, T.vvars freeVars), nNext)
+            fs, T.LetBlo (var, T.Con(thisTag, T.vvars freeVarsCon), nNext)
     | S.IfZero (value, tIf, tElse) ->
             let fs, tIf = walk_term fs tIf in
             let fs, tElse = walk_term fs tElse in

src/tests/rec_factorial.exp

@@ -0,0 +1 @@
+5040

src/tests/rec_factorial.lambda

@@ -0,0 +1,9 @@
+let rec fact = fun n ->
+    ifzero n then
+        1
+    else
+        let sub_val = fact (n - 1) in
+        n * sub_val
+    in
+
+print (fact 7)

src/tests/rec_fibo.exp

@@ -0,0 +1,9 @@
+1
+1
+2
+3
+5
+8
+13
+21
+34

src/tests/rec_fibo.lambda

@@ -0,0 +1,25 @@
+let fibo = fun n ->
+    let rec fibo_inner = fun i -> fun last -> fun last_last ->
+        ifzero (n - i) then
+            last + last_last
+        else
+            fibo_inner (i+1) (last + last_last) last
+    in
+
+    ifzero n then
+        1
+    else ifzero (n - 1) then
+        1
+    else
+        fibo_inner 2 1 1
+    in
+
+let x = print fibo 0 in
+let x = print fibo 1 in
+let x = print fibo 2 in
+let x = print fibo 3 in
+let x = print fibo 4 in
+let x = print fibo 5 in
+let x = print fibo 6 in
+let x = print fibo 7 in
+print fibo 8