This is documentation for Mathematica 4, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)

Set (=)Unset (=.)

SetDelayed

FilledSmallSquarelhs := rhs assigns rhs to be the delayed value of lhs. rhs is maintained in an unevaluated form. When lhs appears, it is replaced by rhs, evaluated afresh each time.

FilledSmallSquare See notes for Set.

FilledSmallSquareSetDelayed has attribute HoldAll, rather than HoldFirst.

FilledSmallSquare You can make assignments of the form lhs := rhs /; test, where test gives conditions for the applicability of each transformation rule. You can make several assignments with the same lhs but different forms of test.

FilledSmallSquarelhs := rhs returns Null if the assignment specified can be performed, and returns $Failed otherwise.

FilledSmallSquare See The Mathematica Book: Section 2.4.8 and Section A.5.2.

FilledSmallSquare See also: TagSetDelayed, Unset, Clear.

Further Examples

Set (=)Unset (=.)