Added "material impliciation" to Booleans.

diff --git a/src/core/boolean.slate b/src/core/boolean.slate
index 91582e8..49bfd12 100644 (file)
--- a/src/core/boolean.slate
+++ b/src/core/boolean.slate
@@ -32,6 +32,9 @@ x@(Boolean traits) eqv: y@(Boolean traits) [x == y].
 "Boolean Exclusive OR."
 x@(Boolean traits) xor: y@(Boolean traits) [x eqv: y not].
 
+"Implication (not entailment)."
+x@(Boolean traits) --> y@(Boolean traits) [x not \/ y].
+
 bool@(Boolean traits) and: block
 "Conditional AND, but it can return the value of the block."
 [bool ifTrue: block ifFalse: [False]].