Add zero-comparator and one-comparator to the sample implementation

2 files changed, 18 insertions, 5 deletions

diff --git a/srfi/228.sld b/srfi/228.sld
index 834f1ce..ebec908 100644
--- a/srfi/228.sld
+++ b/srfi/228.sld
@@ -5,5 +5,8 @@
 	  (srfi 151))
   (export make-wrapper-comparator
           make-product-comparator
-          make-sum-comparator)
+          make-sum-comparator
+
+          one-comparator
+          zero-comparator)
   (include "srfi-228.scm"))
diff --git a/srfi/srfi-228.scm b/srfi/srfi-228.scm
index caca339..b90db54 100644
--- a/srfi/srfi-228.scm
+++ b/srfi/srfi-228.scm
@@ -53,7 +53,7 @@
   (let ((a-cmp (find-tail (type-tests-for? a) comparators)))
     (if (and a-cmp ((comparator-type-test-predicate (car a-cmp)) b))
         a-cmp
-        (let ((b-cmp (find-tail (type-tests-for? a) comparators)))
+        (let ((b-cmp (find-tail (type-tests-for? b) comparators)))
           (if (and b-cmp ((comparator-type-test-predicate (car b-cmp)) a))
               b-cmp
               #f)))))
@@ -84,7 +84,17 @@
          (let ((cmp (%sum-comparator-for comparators x x)))
            ((comparator-hash-function (car cmp)) x)))
        #f)))
-<<<<<<<< HEAD:srfi/composing-comparators.scm
 
-========
->>>>>>>> 58c55b3dfe6ebdfd8770cd69ac08acda24dc4f50:srfi/srfi-228.scm
+(define one-comparator
+  (make-comparator
+   (lambda (x) #t)
+   (lambda (a b) #t)
+   (lambda (a b) #f)
+   (lambda (x) 0)))
+
+(define zero-comparator
+  (make-comparator
+   (lambda (x) #f)
+   (lambda (a b) (error "can't compare" a b))
+   (lambda (a b) (error "can't compare" a b))
+   (lambda (x) (error "can't hash" x))))