diff --git a/cs019/cs019-pre-base.rkt b/cs019/cs019-pre-base.rkt
index a46646e..b15e352 100644
--- a/cs019/cs019-pre-base.rkt
+++ b/cs019/cs019-pre-base.rkt
@@ -4,6 +4,10 @@
 (require (for-syntax "teach.rkt")
          (for-syntax racket/base))
 
+;; FIXME: there's something wrong with the compiler: it's not picking
+;; up that teach-runtime is a dependency.
+(require "teach-runtime.rkt")
+
 (provide cs019-lambda
          cs019-define
          cs019-when
diff --git a/tests/more-tests/basics-cs019.expected b/tests/more-tests/basics-cs019.expected
new file mode 100644
index 0000000..a4d23ae
--- /dev/null
+++ b/tests/more-tests/basics-cs019.expected
@@ -0,0 +1,2 @@
+Running tests...
+All 10 tests passed!
diff --git a/tests/more-tests/sigs-cs019.rkt b/tests/more-tests/sigs-cs019.rkt
new file mode 100755
index 0000000..60089df
--- /dev/null
+++ b/tests/more-tests/sigs-cs019.rkt
@@ -0,0 +1,346 @@
+#lang planet dyoo/whalesong/cs019
+
+
+(define: x : Number$ 3)
+;(define: y : string? 4)
+(check-expect x 3)
+
+
+;; The error should focus around the signature "Number$" here.
+#;(check-violation-highlights 
+ (local [(define: x : Number$ "three")]
+   'huh?)
+ (list "Number$")
+ (list 22))
+
+
+(define: gl : (Listof: Any$) (list 1 "two" true))
+(check-expect gl (list 1 "two" true))
+
+(define: (g [x : Number$]) -> String$ "x")
+(check-expect (g 10) "x")
+#;(check-error (g "x"))
+#;(check-violation-highlights
+ (g "x")
+ (list "Number$")
+ (list 17))
+
+
+(define: (g2 [x : Number$]) -> String$ 'not-a-string)
+#;(check-error (g2 "10"))
+#;(check-error (g2 10))
+#;(check-violation-highlights
+ (g2 "10")
+ (list "Number$")
+ (list 18))
+#;(check-violation-highlights
+ (g2 10)
+ (list "String$")
+ (list 31))
+
+
+(define: (unchk [x : Any$]) -> Number$ (add1 x))
+(check-expect (unchk 10) 11)
+#;(check-error (unchk "x"))
+
+(define: (f [x : Number$] [y : Number$]) -> Number$
+  (+ x y))
+(check-expect (f 10 12) 22)
+
+(define: c1 : Char$ #\c)
+(check-expect c1 #\c)
+
+#;(define: key1 : Key$ "up")
+#;(check-expect key1 "up")
+
+(define: img1 : Image$ (circle 10 "solid" "red"))
+(define: img2 : Image$ (overlay img1 img1))
+(check-expect img1 (circle 10 "solid" "red"))
+; (check-expect img1 img2) fails, expectedly, even though they are visually the same
+
+(define: pos1 : Posn$ (make-posn 5 10))
+(define: pos2 : Posn$ (make-posn 1 2))
+(check-expect (posn-x pos1) 5)
+(check-expect (posn-y pos2) 2)
+
+(define-struct: swf ([f : (Number$ -> Number$)]))
+(define a-swf (make-swf add1))
+(check-expect ((swf-f a-swf) 10) 11)
+#;(check-error (set-swf-f! a-swf 3))
+#;(check-violation-highlights 
+ (set-swf-f! a-swf 3)
+ ;; What should be highlighted is the entire signature
+ (list "(Number$ -> Number$)")
+ (list 26))
+
+
+(define: n*fn->n : (Number$ (Number$ -> Number$) -> Number$)
+  (lambda (n1 fn) (fn n1)))
+(check-expect (n*fn->n 5 add1) 6)
+(check-expect (n*fn->n 10 sub1) 9)
+
+(define broken-swf (make-swf add1))
+(set-swf-f! broken-swf number->string) ;; first-order check succeeds
+#;(check-error ((swf-f broken-swf) 3))  ;; contract violation
+#;(check-violation-highlights
+ ((swf-f broken-swf) 3)
+ (list "Number$")
+ (list 38)) ;; should be pointing to the Number$ in swf-f's range.
+
+(check-expect (let ([a (make-swf add1)])
+                (list ((swf-f a) 10)
+                      (begin (set-swf-f! a sub1)
+                             ((swf-f a) 10))))
+              (list 11 9))
+
+(define Tree$ (or: mt$ nd$))
+(define-struct mt ())
+(define mt$ (Sig: mt?))
+(define-struct: nd ([v : Number$] [l : Tree$] [r : Tree$]))
+
+#;(check-error (set-nd-v! (make-nd 0 (make-mt) (make-mt)) "x"))
+#;(check-violation-highlights
+ (set-nd-v! (make-nd 0 (make-mt) (make-mt)) "x")
+ (list "Number$")
+ (list 25))
+#;(check-error (set-nd-l! (make-nd 0 (make-mt) (make-mt)) "x"))
+#;(check-violation-highlights
+ (set-nd-l! (make-nd 0 (make-mt) (make-mt)) "x")
+ (list "(or: mt$ nd$)")
+ (list 14))
+(check-expect (let ([n (make-nd 0 (make-mt) (make-mt))])
+                (begin
+                  (set-nd-v! n 5)
+                  (set-nd-l! n (make-nd 1 (make-mt) (make-mt)))
+                  n))
+              (make-nd 5 (make-nd 1 (make-mt) (make-mt)) (make-mt)))
+
+(define: (a (t : mt$)) -> Number$
+  (cond
+    [(mt? t) 0]
+    [(nd? t) 1]))
+(check-expect (a (make-mt)) 0)
+#;(check-error (a (make-nd 1 2 3)))
+#;(check-violation-highlights
+ (a (make-nd 1 2 3))
+ (list "(or: mt$ nd$)")
+ (list 14))
+#;(check-error (a 3))
+#;(check-violation-highlights
+ (a 3)
+ (list "(Sig: mt?)")
+ (list 12))
+
+
+(define: (tree-sum (t : Tree$)) -> Number$
+  (cond
+    [(mt? t) 0]
+    [(nd? t) (+ (nd-v t) (tree-sum (nd-l t)) (tree-sum (nd-r t)))]))
+(check-expect (tree-sum (make-nd 10 
+                                 (make-nd 5 (make-mt) (make-mt))
+                                 (make-nd 2 (make-nd 1 (make-mt) (make-mt)) (make-mt))))
+              18)
+#;(check-error (tree-sum (make-nd 10 
+                                (make-nd 5 (make-mt) (make-mt))
+                                (make-nd 2 (make-nd 1 (make-mt) 10) (make-mt)))))
+#;(check-violation-highlights
+ (tree-sum (make-nd 10 
+                    (make-nd 5 (make-mt) (make-mt))
+                    (make-nd 2 (make-nd 1 (make-mt) 10) (make-mt))))
+ (list "(or: mt$ nd$)")
+ (list 14))
+
+
+(define: (prime? [n : (Sig: (lambda (n) (and (positive? n) (integer? n))))]) 
+  -> Boolean$
+  (local ([define (check k)
+            (if (>= k n)
+                true
+                (if (= (remainder n k) 0)
+                    false
+                    (check (add1 k))))])
+    (check 2)))
+(check-expect (prime? 10) false)
+(check-expect (prime? 5) true)
+#;(check-error (prime? -1))
+#;(check-violation-highlights 
+ (prime? -1) 
+ (list "(Sig: (lambda (n) (and (positive? n) (integer? n))))")
+ (list 22))
+#;(check-error (prime? 1.5))
+#;(check-violation-highlights
+ (prime? 1.5)
+ (list "(Sig: (lambda (n) (and (positive? n) (integer? n))))")
+ (list 22))
+
+(define BadSig$ (or: (Number$ -> Number$) Number$))
+;(define: bs : BadSig 3)
+;(define BadSig2 (not: (Number$ -> Number$)))
+
+(define VerySpecialNumber$ (and: Number$ (Sig: positive?) (Sig: even?)))
+(define: vsn : VerySpecialNumber$ 20)
+(check-expect vsn 20)
+;(define: vsn2 : VerySpecialNumber$ 19)
+(define: nvsn : (not: VerySpecialNumber$) 19)
+(check-expect nvsn 19)
+
+(define-struct: p ([x : Number$] [y : Number$]))
+(define: (h [p : p$]) -> Number$
+  (p-x p))
+(check-expect (h (make-p 1 2)) 1)
+(check-expect (h (make-p 3 4)) 3)
+
+(define n->n (Sig: (Number$ -> Number$)))
+(define: a1 : n->n add1)
+(check-expect (a1 5) 6)
+#;(check-error (a1 "x"))
+#;(check-violation-highlights (a1 "x")
+                            (list "Number$")
+                            (list 20))
+
+(define: a2 : (Number$ -> Number$) add1)
+(check-expect (a2 5) 6)
+#;(check-error (a2 "x"))
+#;(check-violation-highlights (a2 "x")
+                            (list "Number$")
+                            (list 15))
+
+(define: s2n : (String$ -> Number$) string->number)
+(check-expect (s2n "123") 123)
+#;(check-error (s2n "xyz")) ;; produces false
+#;(check-violation-highlights (s2n "xyz")
+                            (list "Number$")
+                            (list 27))
+
+(define: (i [f : (Number$ -> Number$)]) -> Number$
+  (f 5))
+(check-expect (i add1) 6)
+#;(check-error (i number->string))
+#;(check-violation-highlights 
+ (i number->string)
+ (list "Number$")
+ (list 29))
+#;(check-error (i string->number))
+;; Unfortunately, the error that comes in isn't a signature error;
+;; it encounters string->number first.
+; #;(check-violation-highlights (i string->number) (list "Number$"))
+
+(define: (j [f : (String$ String$ String$ -> Number$)]) -> Number$
+  (f "12" "34" "56"))
+(check-expect (j (lambda (s1 s2 s3)
+                   (string->number (string-append s1 s2 s3))))
+              123456)
+#;(check-error (j string-append))
+#;(check-violation-highlights
+ (j string-append)
+ (list "Number$")
+ (list 45))
+
+(define: (j2 [f : (String$ String$ -> String$)] [g : (String$ -> String$)]) -> String$
+  (g (f "abc" "def")))
+(check-expect (j2 string-append (lambda (s) (substring s 0 2))) "ab")
+
+(define: (d/dx [f : (Number$ -> Number$)]) -> (Number$ -> Number$)
+  (local [(define: dx : Number$ 0.0001)]
+    (lambda: ([x : Number$]) -> Number$
+      (/ (- (f (+ x dx)) (f x))
+         dx))))
+#;(check-within ((d/dx (lambda: ([x : Number$]) -> Number$ (* x x))) 10) 19 21)
+#;(check-error ((d/dx number->string) 10))
+#;(check-violation-highlights
+ ((d/dx number->string) 10)
+ (list "Number$")
+ (list 32))
+
+#;(check-within
+ ((lambda: ([ddx : ((Number$ -> Number$) -> (Number$ -> Number$))]) -> Number$
+    ((ddx (lambda (x) (* x x))) 10))
+  d/dx)
+ 19 21)
+
+(check-expect (local ([define: x : Number$ 3]) x) 3)
+#;(check-error (local ([define: x : String$ 3]) x))
+#;(check-violation-highlights
+ (local ([define: x : String$ 3]) x)
+ (list "String$")
+ (list 22))
+
+(check-expect (local ([define: (f [x : Number$]) -> String$
+                        (number->string x)])
+                (f 10))
+              "10")
+(check-expect (local ([define: (f [p : (Number$ -> String$)]) -> String$
+                        (p 10)])
+                (f number->string))
+              "10")
+#;(check-error (local ([define: (f [x : Number$]) -> String$
+                       (number->string x)])
+               (f "10")))
+#;(check-violation-highlights
+ (local ([define: (f [x : Number$]) -> String$
+           (number->string x)])
+   (f "10"))
+ (list "Number$")
+ (list 26))
+
+(check-expect (local ([define-struct: m ([v : Number$] [w : String$])])
+                (m-v (make-m 5 "x")))
+              5)
+#;(check-error (local ([define-struct: m ([v : Number$] [w : String$])])
+               (m-v (make-m "x" 5))))
+#;(check-violation-highlights
+ (local ([define-struct: m ([v : Number$] [w : String$])])
+   (m-v (make-m "x" 5)))
+ (list "Number$")
+ (list 33))
+#;(check-error (local ([define-struct: m ([v : Number$] [w : String$])])
+               (m-v (make-m 4 5))))
+#;(check-violation-highlights
+ (local ([define-struct: m ([v : Number$] [w : String$])])
+   (m-v (make-m 4 5)))
+ (list "String$")
+ (list 47))
+
+
+(define: l : (Listof: Number$) (list 1 2 3))
+(check-expect l (list 1 2 3))
+; (define: m : (Listof: Number$) (list 1 2 "X"))
+
+(define: (n [l : (Listof: (Number$ -> Number$))]) -> (Listof: Number$)
+  (map (lambda (f) (f 10)) l))
+(check-expect (n (list add1 sub1)) (list 11 9))
+#;(check-error (n (list add1 number->string)))
+#;(check-violation-highlights
+ (n (list add1 number->string))
+ (list "Number$")
+ (list 38))
+#;(check-error (n (list add1 string->number)))
+
+(define: vs : (Vectorof: String$)
+  (vector "0" "1" "2"))
+(check-expect vs (vector "0" "1" "2"))
+
+(define: (cvts [ns : (Listof: Number$)]) -> (Listof: String$)
+  (local [(define: cv : (Vectorof: ((Listof: String$) -> (Listof: String$)))
+            (vector (lambda (cs) (cons "0" cs))
+                    (lambda (cs) (cons "1" cs))))
+          (define (iter ns)
+            (if (empty? ns)
+                ns
+                ((vector-ref cv (first ns))
+                 (iter (rest ns)))))]
+    (iter ns)))
+(check-expect (cvts empty) empty)
+(check-expect (cvts (list 0 1 0 0)) (list "0" "1" "0" "0"))
+
+
+
+
+(define S (or: 2 3))
+#;(check-error (local [(define: v : S 4)]
+               v))
+#;(check-violation-highlights
+ (local [(define: v : S 4)]
+   v)
+ (list "2")
+ (list 15))
\ No newline at end of file
diff --git a/tests/run-more-tests.rkt b/tests/run-more-tests.rkt
index 1fa497d..6a8838c 100644
--- a/tests/run-more-tests.rkt
+++ b/tests/run-more-tests.rkt
@@ -36,3 +36,4 @@
 (test "more-tests/booleans-cs019.rkt")
 (test "more-tests/checking-cs019.rkt")
 (test "more-tests/sharing-cs019.rkt")
+(test "more-tests/basics-cs019.rkt")
\ No newline at end of file
diff --git a/version.rkt b/version.rkt
index 1a01f11..8cf45cd 100644
--- a/version.rkt
+++ b/version.rkt
@@ -6,4 +6,4 @@
 
 (provide version)
 (: version String)
-(define version "1.45")
+(define version "1.46")