-USING: classes classes.private help.markup help.syntax kernel\r
-math sequences ;\r
-IN: classes.algebra\r
-\r
-ARTICLE: "class-operations" "Class operations"\r
-"Set-theoretic operations on classes:"\r
-{ $subsections\r
- class=\r
- class<\r
- class<=\r
- class-and\r
- class-or\r
- classes-intersect?\r
- flatten-class\r
-} ;\r
-\r
-ARTICLE: "class-linearization" "Class linearization"\r
-"Classes have an intrinsic partial order; given two classes A and B, we either have that A is a subset of B, B is a subset of A, A and B are equal as sets, or they are incomparable. The last two situations present difficulties for method dispatch:"\r
-{ $list\r
- "If a generic word defines a method on a mixin class A and another on class B, and B is the only instance of A, there is an ambiguity because A and B are equal as sets; any object that is an instance of one is an instance of both."\r
- { "If a generic word defines methods on two union classes which are incomparable but not disjoint, for example " { $link sequence } " and " { $link number } ", there is an ambiguity because the generic word may be called on an object that is an instance of both unions." }\r
-}\r
-"The first ambiguity is resolved with a tie-breaker that compares metaclasses. The intrinsic meta-class order, from most-specific to least-specific:"\r
-{ $list\r
- "Built-in classes and tuple classes"\r
- "Predicate classes"\r
- "Union classes"\r
- "Mixin classes"\r
-}\r
-"This means that in the above example, the generic word with methods on a mixin and its sole instance will always call the method for the sole instance, since it is more specific than a mixin class."\r
-$nl\r
-"The second problem is resolved with another tie-breaker. When performing the topological sort of classes, if there are multiple candidates at any given step of the sort, lexicographical order on the class name is used."\r
-$nl\r
-"Operations:"\r
-{ $subsections\r
- class<\r
- sort-classes\r
- smallest-class\r
-}\r
-"Metaclass order:"\r
-{ $subsections rank-class } ;\r
-\r
-HELP: flatten-class\r
-{ $values { "class" class } { "assoc" "an assoc whose keys are classes" } }\r
-{ $description "Outputs a set of builtin and tuple classes whose union is the smallest cover of " { $snippet "class" } "." } ;\r
-\r
-HELP: class<=\r
-{ $values { "first" "a class" } { "second" "a class" } { "?" boolean } }\r
-{ $description "Tests if all instances of " { $snippet "class1" } " are also instances of " { $snippet "class2" } "." }\r
-{ $notes "Classes are partially ordered. This means that if " { $snippet "class1 <= class2" } " and " { $snippet "class2 <= class1" } ", then " { $snippet "class1 <= class2" } ". Also, if " { $snippet "class1 <= class2" } " and " { $snippet "class2 <= class3" } ", then " { $snippet "class1 <= class3" } "." } ;\r
-\r
-HELP: sort-classes\r
-{ $values { "seq" "a sequence of class" } { "newseq" "a new sequence of classes" } }\r
-{ $description "Outputs a linear sort of a sequence of classes. Larger classes come before their subclasses." } ;\r
-\r
-HELP: class-or\r
-{ $values { "first" class } { "second" class } { "class" class } }\r
-{ $description "Outputs the smallest anonymous class containing both " { $snippet "class1" } " and " { $snippet "class2" } "." } ;\r
-\r
-HELP: class-and\r
-{ $values { "first" class } { "second" class } { "class" class } }\r
-{ $description "Outputs the largest anonymous class contained in both " { $snippet "class1" } " and " { $snippet "class2" } "." } ;\r
-\r
-HELP: classes-intersect?\r
-{ $values { "first" class } { "second" class } { "?" boolean } }\r
-{ $description "Tests if two classes have a non-empty intersection. If the intersection is empty, no object can be an instance of both classes at once." } ;\r
-\r
-HELP: smallest-class\r
-{ $values { "classes" "a sequence of class words" } { "class/f" { $maybe class } } }\r
-{ $description "Outputs a minimum class from the given sequence." } ;\r
+USING: classes classes.private help.markup help.syntax kernel
+math sequences ;
+IN: classes.algebra
+
+ARTICLE: "class-operations" "Class operations"
+"Set-theoretic operations on classes:"
+{ $subsections
+ class=
+ class<
+ class<=
+ class-and
+ class-or
+ classes-intersect?
+ flatten-class
+} ;
+
+ARTICLE: "class-linearization" "Class linearization"
+"Classes have an intrinsic partial order; given two classes A and B, we either have that A is a subset of B, B is a subset of A, A and B are equal as sets, or they are incomparable. The last two situations present difficulties for method dispatch:"
+{ $list
+ "If a generic word defines a method on a mixin class A and another on class B, and B is the only instance of A, there is an ambiguity because A and B are equal as sets; any object that is an instance of one is an instance of both."
+ { "If a generic word defines methods on two union classes which are incomparable but not disjoint, for example " { $link sequence } " and " { $link number } ", there is an ambiguity because the generic word may be called on an object that is an instance of both unions." }
+}
+"The first ambiguity is resolved with a tie-breaker that compares metaclasses. The intrinsic meta-class order, from most-specific to least-specific:"
+{ $list
+ "Built-in classes and tuple classes"
+ "Predicate classes"
+ "Union classes"
+ "Mixin classes"
+}
+"This means that in the above example, the generic word with methods on a mixin and its sole instance will always call the method for the sole instance, since it is more specific than a mixin class."
+$nl
+"The second problem is resolved with another tie-breaker. When performing the topological sort of classes, if there are multiple candidates at any given step of the sort, lexicographical order on the class name is used."
+$nl
+"Operations:"
+{ $subsections
+ class<
+ sort-classes
+ smallest-class
+}
+"Metaclass order:"
+{ $subsections rank-class } ;
+
+HELP: flatten-class
+{ $values { "class" class } { "assoc" "an assoc whose keys are classes" } }
+{ $description "Outputs a set of builtin and tuple classes whose union is the smallest cover of " { $snippet "class" } "." } ;
+
+HELP: class<=
+{ $values { "first" "a class" } { "second" "a class" } { "?" boolean } }
+{ $description "Tests if all instances of " { $snippet "class1" } " are also instances of " { $snippet "class2" } "." }
+{ $notes "Classes are partially ordered. This means that if " { $snippet "class1 <= class2" } " and " { $snippet "class2 <= class1" } ", then " { $snippet "class1 <= class2" } ". Also, if " { $snippet "class1 <= class2" } " and " { $snippet "class2 <= class3" } ", then " { $snippet "class1 <= class3" } "." } ;
+
+HELP: sort-classes
+{ $values { "seq" "a sequence of class" } { "newseq" "a new sequence of classes" } }
+{ $description "Outputs a linear sort of a sequence of classes. Larger classes come before their subclasses." } ;
+
+HELP: class-or
+{ $values { "first" class } { "second" class } { "class" class } }
+{ $description "Outputs the smallest anonymous class containing both " { $snippet "class1" } " and " { $snippet "class2" } "." } ;
+
+HELP: class-and
+{ $values { "first" class } { "second" class } { "class" class } }
+{ $description "Outputs the largest anonymous class contained in both " { $snippet "class1" } " and " { $snippet "class2" } "." } ;
+
+HELP: classes-intersect?
+{ $values { "first" class } { "second" class } { "?" boolean } }
+{ $description "Tests if two classes have a non-empty intersection. If the intersection is empty, no object can be an instance of both classes at once." } ;
+
+HELP: smallest-class
+{ $values { "classes" "a sequence of class words" } { "class/f" { $maybe class } } }
+{ $description "Outputs a minimum class from the given sequence." } ;
projects / factor.git / blobdiff