render labelled decision trees as graphviz diagrams

examples/simplify.tess

@@ -0,0 +1,11 @@
+data Expr = Lit Int | Add Expr Expr | Mul Expr Expr | Neg Expr
+
+match simplify (e : Expr) : Expr =
+  | Add (Lit 0) x -> x
+  | Add x (Lit 0) -> x
+  | Mul (Lit 0) x -> Lit 0
+  | Mul x (Lit 0) -> Lit 0
+  | Mul (Lit 1) x -> x
+  | Mul x (Lit 1) -> x
+  | Neg (Neg x) -> x
+  | e -> e