This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)
 Documentation / Mathematica / Built-in Functions / Programming / Assignments  /

  • lhs := 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.
  • See notes for Set.
  • SetDelayed has attribute HoldAll, rather than HoldFirst.
  • 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.
  • lhs := rhs returns Null if the assignment specified can be performed, and returns $Failed otherwise.
  • See the Mathematica book: Section 2.4.8Section A.5.2.
  • See also: TagSetDelayed, Unset, Clear.

    Further Examples

    See the Further Examples for Set.