 { $values { "elements" "a list of classoids" } }
 { $description "Marks the beginning of a literal " { $link anonymous-intersection } " class." } ;
 
+HELP: maybe{
+{ $syntax "maybe{ elements... }" }
+{ $values { "elements" "a list of classoids" } }
+{ $description "Marks the beginning of a literal " { $link maybe } " class." } ;
+
+HELP: not{
+{ $syntax "not{ elements... }" }
+{ $values { "elements" "a list of classoids" } }
+{ $description "Marks the beginning of a literal " { $link anonymous-complement } " class." } ;
+
+HELP: union{
+{ $syntax "union{ elements... }" }
+{ $values { "elements" "a list of classoids" } }
+{ $description "Marks the beginning of a literal " { $link anonymous-union } " class." } ;
+
+{ POSTPONE: intersection{ POSTPONE: union{ POSTPONE: not{ POSTPONE: maybe{ } related-words
+
 HELP: H{
 { $syntax "H{ { key value }... }" }
 { $values { "key" object } { "value" object } }

{ $values { "members" "a list of objects" } }
{ $description "Marks the beginning of a literal hash set, given as a list of its members. Literal hashtables are terminated by " { $link POSTPONE: } } "." }
{ $examples { $code "HS{ 3 \"foo\" }" } } ;

HELP: C{
{ $syntax "C{ real-part imaginary-part }" }

} ;

{ POSTPONE: call( POSTPONE: execute( } related-words

HELP: BUILTIN:
{ $syntax "BUILTIN: class slots ... ;" }
{ $values { "class" "a builtin class" } { "definition" "a word definition" } }
{ $description "A representation of a builtin class from the VM. This word cannot define new builtins but is meant to provide a paper trail to which vocabularies define the builtins. To define new builtins requires adding them to the VM." } ;

HELP: PRIMITIVE:
{ $syntax "PRIMITIVE: word ( stack -- effect )" }
{ $description "A reference to a primitive word of from the VM. This word cannot define new primitives but is meant to provide a paper trail to which vocabularies define the primitives. To define new primitves requires adding them to the VM." } ;

HELP: MEMO:
{ $syntax "MEMO: word ( stack -- effect ) definition... ;" }
{ $values { "word" "a new word to define" } { "definition" "a word definition" } }
{ $description "Defines the given word at parse time as one which memoizes its output given a particular input. The stack effect is mandatory." } ;

HELP: IDENTITY-MEMO:
{ $syntax "IDENTITY-MEMO: word ( stack -- effect ) definition... ;" }
{ $values { "word" "a new word to define" } { "definition" "a word definition" } }
{ $description "Defines the given word at parse time as one which memoizes its output given a particular input which is identical to another input. The stack effect is mandatory." } ;

HELP: IDENTITY-MEMO::
{ $syntax "IDENTITY-MEMO:: word ( stack -- effect ) definition... ;" }
{ $values { "word" "a new word to define" } { "definition" "a word definition" } }
{ $description "Defines the given word at parse time as one which memoizes its output given a particular input with locals which is identical to another input. The stack effect is mandatory." } ;
