@@ -1,15 +1,15 @@
-// Package diff provides a diff implementation
-// for finite, indexable sequences with comparable elements
+// Package diff provides a diff algorithm implementation
+// for finite, indexable sequences with comparable elements.
 package diff
 
 import (
 	bits "0dev.org/bits"
 )
 
 // Interface abstracts the required knowledge to perform a diff
-// on any two comparable, fixed-length sequences
+// on any two fixed-length sequences with comparable elements.
 type Interface interface {
 	// The sequences' lengths
 	Len() (int, int)
 	// True when the sequences' elements at those indices are equal
 	Equal(int, int) bool
@@ -126,5 +126,21 @@
 			inMatch = false // ... and reset the current one
 		}
 	}
 	return
 }
+
+// A diff.Interface implementation with plugable Equal function
+type D struct {
+	Len1, Len2 int
+	EqualFunc  func(i, j int) bool
+}
+
+// Required per diff.Interface
+func (d D) Len() (int, int) {
+	return d.Len1, d.Len2
+}
+
+// Required per diff.Interface
+func (d D) Equal(i, j int) bool {
+	return d.EqualFunc(i, j)
+}