HELP TWIDDLYBRA                                    Steven Hardy Mar 1982
                                         Updated: Adrian Howard Mar 1992

Twiddly brackets, "{" and "}", tell the POP-11 system to build a vector
of the enclosed items. For example, below is a vector of words and
numbers:

    {2 cats 3 dogs 5 birds}

Vectors can be nested. Percent symbols (%) and up-arrows (^ and ^^) can
be used within a vector expression to cause part of the expression to be
evaluated rather than quoted, e.g.

    vars n1=3, n2=5, n3=7;

    { ^n1 cats ^n2 dogs ^n3 birds }=>
    ** {3 cats 5 dogs 7 birds}

Twiddly brackets may be preceded by -cons_with- to create other
structures than vectors (see HELP *CONS_WITH.)

See TEACH *BRACKETS for a tutorial introduction to the use of brackets
in POP-11, and TEACH *ARROW for the use of up-arrows.

Also see:

    * PERCENT   --- Uses of the % symbol in POP-11

    * INITV     --- Construction of vectors
    * CONSVECTOR

    * SUBSCRV   --- Accessing and updating vector elements

    * SQUAREBRA --- Constructing lists using square brackets
    * ROUNDBRA  --- The use of round brackets in POP-11
    * #_<       --- Compilation brackets
    * #|        --- Stack counting brackets


--- C.all/help/twiddlybra
--- Copyright University of Sussex 1992. All rights reserved. ----------
