         ]
     } 2|| [ "$values don't match stack effect" throw ] unless ;
 
+: check-nulls ( element -- )
+    \ $values swap elements
+    null swap deep-member?
+    [ "$values should not contain null" throw ] when ;
+
 : check-see-also ( element -- )
     \ $see-also swap elements [
         rest dup prune [ length ] bi@ assert=

        dup '[
            _ dup word-help
            [ check-values ]
            [ nip [ check-see-also ] [ check-markup ] bi ] 2bi
        ] check-something
    ] [ drop ] if ;

: check-words ( words -- ) [ check-word ] each ;

: check-article ( article -- )
    [ with-interactive-vocabs ] vocabs-quot set
    dup '[ _ article-content check-markup ] check-something ;

: files>vocabs ( -- assoc )
    vocabs

combinators combinators.short-circuit splitting debugger
hashtables sorting effects vocabs vocabs.loader assocs editors
continuations classes.predicate macros math sets eval
vocabs.parser words.symbol values grouping unicode.categories
sequences.deep ;
IN: help.lint

SYMBOL: vocabs-quot
