diff --git a/turnstile/examples/rosette/rosette2.rkt b/turnstile/examples/rosette/rosette2.rkt
new file mode 100644
index 0000000..da1a157
--- /dev/null
+++ b/turnstile/examples/rosette/rosette2.rkt
@@ -0,0 +1,65 @@
+#lang turnstile
+(extends "../stlc.rkt")
+
+(require 
+ (only-in "../stlc+union.rkt" prune+sort current-sub?)
+ (prefix-in C (only-in "../stlc+union+case.rkt" PosInt Zero NegInt Float Bool [U U*] case-> →))
+ (only-in "../stlc+union+case.rkt" [~U* ~CU*] [~case-> ~Ccase->] [~→ ~C→]))
+
+(define-syntax (CU stx)
+  (syntax-parse stx
+    [(_ . tys)
+     #:with tys+ (stx-map (current-type-eval) #'tys)
+     #:fail-unless (stx-andmap concrete? #'tys+)
+                   "CU require concrete arguments"
+     #'(CU* . tys+)]))
+
+;; internal symbolic union constructor
+(define-type-constructor U* #:arity >= 0)
+(define-syntax (U stx)
+  (syntax-parse stx
+    [(_ . tys)
+     ;; canonicalize by expanding to U*, with only (sorted and pruned) leaf tys
+     #:with ((~or (~U* ty1- ...) (~CU* ty2- ...) ty3-) ...) (stx-map (current-type-eval) #'tys)
+     #:with tys- (prune+sort #'(ty1- ... ... ty2- ... ... ty3- ...))
+     #'(U* . tys-)]))
+
+(begin-for-syntax
+  (define (concrete? t)
+    (not (U*? t))))
+
+(begin-for-syntax
+  (define (sub? t1 t2)
+    ; need this because recursive calls made with unexpanded types
+   ;; (define τ1 ((current-type-eval) t1))
+   ;; (define τ2 ((current-type-eval) t2))
+    ;; (printf "t1 = ~a\n" (syntax->datum t1))
+    ;; (printf "t2 = ~a\n" (syntax->datum t2))
+    (or 
+     ((current-type=?) t1 t2)
+     (syntax-parse (list t1 t2)
+       ; 2 U types, subtype = subset
+       [((~CU* . ts1) _)
+        (for/and ([t (stx->list #'ts1)])
+          ((current-sub?) t t2))]
+       ; 1 U type, 1 non-U type. subtype = member
+       [(_ (~CU* . ts2))
+        (for/or ([t (stx->list #'ts2)])
+          ((current-sub?) t1 t))]
+       ; 2 case-> types, subtype = subset
+       [(_ (~Ccase-> . ts2))
+        (for/and ([t (stx->list #'ts2)])
+          ((current-sub?) t1 t))]
+       ; 1 case-> , 1 non-case->
+       [((~Ccase-> . ts1) _)
+        (for/or ([t (stx->list #'ts1)])
+          ((current-sub?) t t2))]
+       [((~C→ s1 ... s2) (~C→ t1 ... t2))
+        (and (subs? #'(t1 ...) #'(s1 ...))
+             ((current-sub?) #'s2 #'t2))]
+       [_ #f])))
+  (current-sub? sub?)
+  (current-typecheck-relation sub?)
+  (define (subs? τs1 τs2)
+    (and (stx-length=? τs1 τs2)
+         (stx-andmap (current-sub?) τs1 τs2))))
diff --git a/turnstile/examples/stlc+union.rkt b/turnstile/examples/stlc+union.rkt
index 63ca9e0..583d2d0 100644
--- a/turnstile/examples/stlc+union.rkt
+++ b/turnstile/examples/stlc+union.rkt
@@ -4,7 +4,7 @@
 (reuse define-type-alias #:from "stlc+reco+var.rkt")
 (provide Int Num Nat U
          define-named-type-alias
-         (for-syntax current-sub?))
+         (for-syntax current-sub? prune+sort))
 
 ;; Simply-Typed Lambda Calculus, plus union types
 ;; Types:
@@ -32,8 +32,12 @@
 (define-type-constructor U* #:arity > 0)
 
 (define-for-syntax (prune+sort tys)
-  (define ts (stx->list tys))
-  (stx-sort (remove-duplicates (stx->list tys) typecheck?)))
+  (stx-sort 
+   (remove-duplicates 
+    (stx->list tys)
+    ;; remove dups keeps first element
+    ;; but we want to keep supertype
+    (lambda (x y) (typecheck? y x)))))
   
 (define-syntax (U stx)
   (syntax-parse stx
diff --git a/turnstile/examples/tests/rosette/rosette2-tests.rkt b/turnstile/examples/tests/rosette/rosette2-tests.rkt
new file mode 100644
index 0000000..62cacfa
--- /dev/null
+++ b/turnstile/examples/tests/rosette/rosette2-tests.rkt
@@ -0,0 +1,127 @@
+#lang s-exp "../../rosette/rosette2.rkt"
+(require "../rackunit-typechecking.rkt")
+
+;; (check-type (sub1 10) : Nat -> 9)
+;; (check-type (sub1 0) : NegInt -> -1)
+;; (check-type (sub1 -1) : NegInt -> -2)
+
+;; (check-type bv : (case-> (→ Int BVPred BV)
+;;                          (→ Int PosInt BV)))
+;; (typecheck-fail (bv "1" 2) #:with-msg "expected.*Int.*given.*String")
+;; (check-type (bv 1 2) : BV -> (bv 1 (bvpred 2)))
+;; (check-type (bv 1 (bvpred 2)) : BV -> (bv 1 (bvpred 2)))
+
+;; (typecheck-fail (bv 0 0) #:with-msg "expected.*PosInt.*given.*Zero")
+;; (check-type bitvector : (→ PosInt BVPred))
+;; (check-type (bitvector 3) : BVPred)
+;; (typecheck-fail ((bitvector 4) 1))
+;; (check-type ((bitvector 4) (bv 10 (bvpred 4))) :  Bool)
+
+;; ;; same as above, but with bvpred
+;; (check-type bvpred : (→ PosInt BVPred))
+;; (check-type (bvpred 3) : BVPred)
+;; (typecheck-fail ((bvpred 4) 1))
+;; (check-type ((bvpred 4) (bv 10 (bvpred 4))) :  Bool)
+;; ;; typed rosette catches this during typechecking, 
+;; ;; whereas untyped rosette uses a runtime exn
+;; (typecheck-fail (bvpred -1) #:with-msg "expected PosInt, given NegInt")
+;; ;(check-runtime-exn (bvpred -1))
+
+;; (typecheck-fail (bitvector? "2"))
+;; (check-type (bitvector? (bitvector 10)) : Bool -> #t)
+;; (typecheck-fail (bvpred? "2"))
+;; (check-type (bvpred? (bvpred 10)) : Bool -> #t)
+
+;; ;; bvops
+;; (check-type (bveq (bv 1 (bvpred 3)) (bv 1 (bvpred 3))) : Bool -> #t)
+;; (typecheck-fail (bveq (bv 1 (bvpred 3)) 1))
+;; (check-type (bveq (bv 1 (bvpred 2)) (bv 1 (bvpred 3))) : Bool) ; -> runtime exn
+;; (check-runtime-exn (bveq (bv 1 (bvpred 2)) (bv 1 (bvpred 3))))
+
+;; ;; non-primop bvops
+;; (check-type (bvand (bv -1 (bvpred 4)) (bv 2 (bvpred 4))) : BV 
+;;             -> (bv 2 (bvpred 4)))
+;; (check-type (bvor  (bv 0 (bvpred 3))  (bv 1 (bvpred 3))) : BV 
+;;             -> (bv 1 (bvpred 3)))
+;; (check-type (bvxor (bv -1 (bvpred 5)) (bv 1 (bvpred 5))) : BV 
+;;             -> (bv -2 (bvpred 5)))
+
+;; ;; examples from rosette guide
+;; (check-type (bvand (bv -1 4) (bv 2 4)) : BV -> (bv 2 4))
+;; (check-type (bvor  (bv 0 3)  (bv 1 3)) : BV -> (bv 1 3))
+;; (check-type (bvxor (bv -1 5) (bv 1 5)) : BV -> (bv -2 5))
+
+;; (define-symbolic b boolean? : Bool)
+;; (check-type (bvand (bv -1 4) (if b (bv 3 4) (bv 2 4))) : BV 
+;;             -> (if b (bv 3 4) (bv 2 4)))
+
+;; (check-type (bvshl  (bv 1 4) (bv 2 4)) : BV -> (bv 4 4))
+;; (check-type (bvlshr (bv -1 3) (bv 1 3)) : BV -> (bv 3 3))
+;; (check-type (bvashr (bv -1 5) (bv 1 5)) : BV -> (bv -1 5))
+;; ;; TODO: see issue #23
+;; (check-type (bvshl (bv -1 4) (if b (bv 3 4) (bv 2 4))) : BV)
+
+;; (check-type (bvneg (bv -1 4)) : BV -> (bv 1 4))
+;; (check-type (bvneg (bv 0 4)) : BV -> (bv 0 4))
+;; (define-symbolic z (bitvector 3) : BV)
+;; (check-type (bvneg z) : BV)
+;; (check-type (bvadd (bv -1 4) (bv 2 4)) : BV -> (bv 1 4))
+;; (check-type (bvsub (bv 0 3)  (bv 1 3)) : BV -> (bv -1 3))
+;; (check-type (bvmul (bv -1 5) (bv 1 5)) : BV -> (bv -1 5))
+;; ;; TODO: see issue #23
+;; (check-type (bvadd (bv -1 4) (bv 2 4) (if b (bv 1 4) (bv 3 4))) : BV)
+;; (check-type (bvsdiv (bv -3 4) (bv 2 4)) : BV -> (bv -1 4))
+;; (check-type (bvudiv (bv -3 3) (bv 2 3)) : BV -> (bv 2 3))
+;; (check-type (bvsmod (bv 1 5) (bv 0 5)) : BV -> (bv 1 5))
+;; (check-type (bvsrem (bv -3 4) (if b (bv 2 4) (bv 3 4))) : BV 
+;;             -> (if b (bv -1 4) (bv 0 4)))
+
+;; (check-type (concat (bv -1 4) (bv 0 1) (bv -1 3)) : BV -> (bv -9 8))
+;; (check-type (concat (bv -1 4) (if b (bv 0 1) (bv 0 2)) (bv -1 3)) : BV
+;;             -> (if b (bv -9 8) (bv -25 9)))
+
+;; (check-type (extract 2 1 (bv -1 4)) : BV -> (bv -1 2))
+;; (check-type (extract 3 3 (bv 1 4)) : BV -> (bv 0 1))
+;; (define-symbolic i j integer? : Int)
+;; (check-type (extract i j (bv 1 2)) : BV)
+;; ;            -> {[(&& (= 0 j) (= 1 i)) (bv 1 2)] ...})
+
+;; (check-type (sign-extend (bv -3 4) (bitvector 6)) : BV -> (bv -3 6))
+;; (check-type (zero-extend (bv -3 4) (bitvector 6)) : BV -> (bv 13 6))
+;; (define-symbolic c boolean? : Bool)
+;; (check-type (zero-extend (bv -3 4) (if b (bitvector 5) (bitvector 6))) 
+;;   : BV -> (if b (bv 13 5) (bv 13 6)))
+;; #;(check-type (zero-extend (bv -3 4) (if b (bitvector 5) "bad"))
+;;   : BV -> (bv 13 5))
+;; (check-type (zero-extend (bv -3 4) (if c (bitvector 5) (bitvector 1))) 
+;;   : BV -> (bv 13 5))
+
+;; (check-type (bitvector->integer (bv -1 4)) : Int -> -1)
+;; (check-type (bitvector->natural (bv -1 4)) : Int -> 15)
+;; (check-type (bitvector->integer (if b (bv -1 3) (bv -3 4))) 
+;;   : Int -> (if b -1 -3))
+;; ;(check-type (bitvector->integer (if b (bv -1 3) "bad")) : BV -> -1)
+;; (check-type (integer->bitvector 4 (bitvector 2)) : BV -> (bv 0 2))
+;; (check-type (integer->bitvector 15 (bitvector 4)) : BV -> (bv -1 4))
+;; #;(check-type (integer->bitvector (if b pi 3) 
+;;               (if c (bitvector 5) (bitvector 6))) 
+;;   : BV -> {[c (bv 3 5)] [(! c) (bv 3 6)]})
+;; (check-type (integer->bitvector 3
+;;               (if c (bitvector 5) (bitvector 6))) 
+;;   : BV -> (if c (bv 3 5) (bv 3 6)))
+
+;; ;; case-> subtyping
+;; (check-type ((λ ([f : (→ Int Int)]) (f 10)) add1) : Int -> 11)
+;; (check-type ((λ ([f : (case-> (→ Int Int))]) (f 10)) add1) : Int -> 11)
+;; (check-type ((λ ([f : (case-> (→ Nat Nat)
+;;                               (→ Int Int))]) (f 10)) add1) : Int -> 11)
+;; (check-not-type ((λ ([f : (case-> (→ Int Int))]) (f 10)) add1) : Nat)
+;; (check-type ((λ ([f : (case-> (→ Nat Nat)
+;;                               (→ Int Int))]) (f 10)) add1) : Nat -> 11)
+;; (typecheck-fail ((λ ([f : (case-> (→ Zero Zero)
+;;                                   (→ Int Int))]) (f 10)) add1) 
+;;  #:with-msg
+;;  (string-append "expected \\(case-> \\(→ Zero Zero\\) \\(→ Int Int\\)\\), "
+;;                 "given \\(case-> \\(→ NegInt \\(U NegInt Zero\\)\\) \\(→ Zero PosInt\\) "
+;;                 "\\(→ PosInt PosInt\\) \\(→ Nat PosInt\\) \\(→ Int Int\\)\\)"))
+