add an "nspin" generalization

basis/generalizations/generalizations-docs.factor

@@ -303,6 +303,12 @@ HELP: ntuck
 }
 { $description "A generalization of " { $link tuck } " that can work for any stack depth. The top item will be copied and placed " { $snippet "n" } " items down on the stack." } ;
 
+HELP: nspin
+{ $values
+    { "n" integer }
+}
+{ $description "A generalization of " { $link spin } " that can work for any stack depth. The top " { $snippet "n" } " items will be reversed in order." } ;
+
 ARTICLE: "sequence-generalizations" "Generalized sequence operations"
 { $subsections
     narray
@@ -321,6 +327,7 @@ ARTICLE: "shuffle-generalizations" "Generalized shuffle words"
     nnip
     ndrop
     ntuck
+    nspin
     mnswap
     nweave
 } ;

basis/generalizations/generalizations-tests.factor

@@ -26,6 +26,8 @@ IN: generalizations.tests
 { 0 } [ 0 1 2 3 4 4 ndrop ] unit-test
 [ [ 1 ] 5 ndip ] must-infer
 [ 1 2 3 4 ] [ 2 3 4 [ 1 ] 3 ndip ] unit-test
+[ 5 nspin ] must-infer
+[ 1 5 4 3 2 ] [ 1 2 3 4 5 4 nspin ] unit-test
 
 [ 1 2 3 4 5 [ drop drop drop drop drop 2 ] 5 nkeep ] must-infer
 { 2 1 2 3 4 5 } [ 1 2 3 4 5 [ drop drop drop drop drop 2 ] 5 nkeep ] unit-test

basis/generalizations/generalizations.factor

@@ -104,3 +104,6 @@ MACRO: nbi-curry ( n -- )
     [ narray concat ] dip like ; inline
 
 : nappend ( n -- seq ) narray concat ; inline
+
+MACRO: nspin ( n -- )
+    [ [ ] ] swap [ swap [ ] curry compose ] n*quot [ call ] 3append ;