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expr

1977 Version of ANSI Standard

3.3 Expressions expr

Expressions are made up of expression atoms separated by binary string, arithmetic, or truth-valued operators.

    expr::= expratom [ exprtail ] ...

See also the transition diagram for expr.

    exprtail::=






binaryop
[ ' ] truthop


expratom

[ ' ] ? pattern





    binaryop::=






_
+
-
*
/
\
#







      (Note: underscore)

(Note: hyphen)



See also the transition diagram for binaryop.

    truthop::=

relation
logicalop


See also the transition diagram for truthop.

    relation::=




=
<
>
[
]





    logicalop::=

&
!


The order of evaluation is as follows:

  1. Evaluate the left-hand expratom.
  2. If an exprtail is present immediately to the right, evaluate its expratom or pattern and apply its operator.
  3. Repeat step b. as necessary, moving to the right.

In the language of operator precedence, this sequence implies that all binary string, arithmetic, and truth-valued operators are at the same precedence level and are applied in left-to-right order.

Any attempt to evaluate an expratom containing an lvn, gvn, or svn with an undefined value is erroneous.

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Copyright © Standard Documents; 1977-2024 MUMPS Development Committee;
Copyright © Examples: 1995-2024 Ed de Moel;
Copyright © Annotations: 2003-2008 Jacquard Systems Research
Copyright © Annotations: 2008-2024 Ed de Moel.

This page most recently updated on 15-Nov-2023, 09:47:42.

For comments, contact Ed de Moel (demoel@jacquardsystems.com)