diff --git a/functions.rkt b/functions.rkt
index ebf6ff1..1e7e79c 100644
--- a/functions.rkt
+++ b/functions.rkt
@@ -27,7 +27,7 @@
    enumerate-boolean-functions/pv enumerate-boolean-functions/list
    random-boolean-table random-boolean-function random-boolean-function/list
 
-   (struct-out tbf) tbf-w tbf-θ boolean->01/vector)
+   (struct-out tbf) tbf-w tbf-θ boolean->01/vector apply-tbf)
 
   (module+ test
     (require typed/rackunit))
@@ -368,6 +368,22 @@
     (test-case "boolean->01/vector"
       (check-equal? (boolean->01/vector #(#t #f #f)) #(1 0 0))))
 
+  (: apply-tbf (-> tbf (Vectorof (U Zero One)) (U Zero One)))
+  (define (apply-tbf tbf inputs)
+    (any->01
+     (>
+      ;; The scalar product between the inputs and the weights.
+      (for/sum ([x (in-vector inputs)]
+                [w (in-vector (tbf-w tbf))]) : Real
+        (* x w))
+      (tbf-θ tbf))))
+
+  (module+ test
+    (test-case "apply-tbf"
+      (define f1 (tbf #(2 -2) 1))
+      (check-equal? (tabulate/pv/01 2 (pvλ (x y) (apply-tbf f1 (vector x y))))
+                    '((0 0 0) (0 1 0) (1 0 1) (1 1 0)))))
+
   (module untyped racket
     (module+ test
       (require rackunit))
@@ -454,7 +470,7 @@
  enumerate-boolean-functions/pv enumerate-boolean-functions/list
  random-boolean-table random-boolean-function random-boolean-function/list
 
- (struct-out tbf) tbf-w tbf-θ boolean->01/vector)
+ (struct-out tbf) tbf-w tbf-θ boolean->01/vector apply-tbf)
 
 (require (rename-in (submod 'typed untyped)
                     [tabulate tabulate/untyped]
@@ -463,7 +479,6 @@
 (provide
  ;; Functions
  (contract-out
-  [apply-tbf (-> tbf? (vectorof (or/c 0 1)) (or/c 0 1))]
   [apply-tbf/boolean (-> tbf? (vectorof boolean?) boolean?)]
   [list->tbf (-> (cons/c number? (cons/c number? (listof number?))) tbf?)]
   [lists->tbfs (-> (listof (listof number?)) (listof tbf?))]
@@ -486,26 +501,6 @@
 ;;; Threshold Boolean functions
 ;;; ===========================
 
-;;; Applies the TBF to its inputs.
-;;;
-;;; Applying a TBF consists in multiplying the weights by the
-;;; corresponding inputs and comparing the sum of the products to the
-;;; threshold.
-(define (apply-tbf tbf inputs)
-  (any->01
-   (>
-    ;; The scalar product between the inputs and the weights
-    (for/sum ([x (in-vector inputs)]
-              [w (in-vector (tbf-w tbf))])
-      (* x w))
-    (tbf-θ tbf))))
-
-(module+ test
-  (test-case "apply-tbf"
-    (define f1 (tbf #(2 -2) 1))
-    (check-equal? (tabulate/01 (λ (x y) (apply-tbf f1 (vector x y))))
-                  '((0 0 0) (0 1 0) (1 0 1) (1 1 0)))))
-
 ;;; Like apply-tbf, but takes Boolean values as inputs and outputs a
 ;;; boolean value.
 (define (apply-tbf/boolean tbf inputs)
diff --git a/scribblings/functions.scrbl b/scribblings/functions.scrbl
index 4460808..1a11c42 100644
--- a/scribblings/functions.scrbl
+++ b/scribblings/functions.scrbl
@@ -392,6 +392,19 @@ Converts a Boolean vector to a vector of zeros and ones.
 (boolean->01/vector #(#t #f #f))
 ]}
 
+@defproc[(apply-tbf [t tbf] [inputs (Vectorof (U Zero One))]) (U Zero One)]{
+
+Applies the TBF to its inputs.
+
+Applying a TBF consists in multiplying the weights by the corresponding inputs
+and comparing the sum of the products to the threshold.  If the product is
+above the threshold, the function is 1, otherwise it is 0.
+
+@examples[#:eval functions-evaluator
+(define simple-tbf (tbf #(2 -2) 1))
+(tabulate/pv/01 2 (pvλ (x y) (apply-tbf simple-tbf (vector x y))))
+]}
+
 @section[#:tag "fuctions/untyped"]{Untyped definitions}
 
 @defmodule[(submod dds/functions typed untyped)]