document and fix stack effect for 2cleave, 3cleave

core/combinators/combinators-docs.factor

@@ -16,6 +16,10 @@ $nl
 { $subsection while }
 "Generalization of " { $link bi } " and " { $link tri } ":"
 { $subsection cleave }
+"Generalization of " { $link 2bi } " and " { $link 2tri } ":"
+{ $subsection 2cleave }
+"Generalization of " { $link 3bi } " and " { $link 3tri }  ":"
+{ $subsection 3cleave }
 "Generalization of " { $link bi* } " and " { $link tri* } ":"
 { $subsection spread }
 "Two combinators which abstract out nested chains of " { $link if } ":"
@@ -50,6 +54,16 @@ HELP: cleave
     }
 } ;
 
+HELP: 2cleave
+{ $values { "x" object } { "y" object }
+          { "seq" "a sequence of quotations with stack effect " { $snippet "( x y -- ... )" } } }
+{ $description "Applies each quotation to the two objects in turn." } ;
+
+HELP: 3cleave
+{ $values { "x" object } { "y" object } { "z" object }
+          { "seq" "a sequence of quotations with stack effect " { $snippet "( x y z -- ... )" } } }
+{ $description "Applies each quotation to the three objects in turn." } ;
+
 { bi tri cleave } related-words
 
 HELP: spread

core/combinators/combinators.factor

@@ -13,14 +13,14 @@ IN: combinators
     [ [ keep ] curry ] map concat [ drop ] append [ ] like ;
 
 ! 2cleave
-: 2cleave ( x seq -- )
+: 2cleave ( x y seq -- )
     [ 2keep ] each 2drop ;
 
 : 2cleave>quot ( seq -- quot )
     [ [ 2keep ] curry ] map concat [ 2drop ] append [ ] like ;
 
 ! 3cleave
-: 3cleave ( x seq -- )
+: 3cleave ( x y z seq -- )
     [ 3keep ] each 3drop ;
 
 : 3cleave>quot ( seq -- quot )