MUMPS Programming/syntax

Basic MUMPS Syntax - Lines, Spaces, WhiteSpace, Comments

MUMPS syntax was designed to be concise in a time of scarce memory. This serves a purpose now in that programs are cognitively concise: a lot more fits in view on a screen or on a page of paper.

• The basic language structure is command command-separator argument.
  • The command may be one of the MUMPS commands, like "SET" or "WRITE"
  • The command-separator is written as a single space (or blank) between command (SET) and the arguments.
  • The argument depends on the command.
    • The argument can be a list of single-arguments (separated by commas) or a single-argument.
    • Each single-argument usually is in the form of an expression or group of expression, separated by colons.
• separating each command may be multiple spaces for readability.
• Another command may follow a space on the same line.

        SET X=1    SET Y=2

• Whitespace - eol is NOT treated as equivalent to space. Each has different role in MUMPS.
• Tabs are also NOT equivalent to a space, but are sometimes treated like space to delineate a label. Traditional MUMPS editors (IDEs) sometimes treat tabs specially, but do not put the tab character into the MUMPS routine.
• Lines are significant to the syntax as each line starts with a tag(line label) and a space or a space when there is no label.
• Comments start with semicolon (;) and go to the end of the line. A line may start with ; and is all comment.
• There is no command termination character (like ; in java or Perl) other than the eol or a space following the argument.
• Assignment requires the explicit command SET or S

        SET X=1,Y=2  ;   either form full or abbreviated command S
        S X=1,Y=2    ;  

• There is no syntactic role for braces {}
• Expressions are grouped by parenthesis

• Programs ('routines' in traditional MUMPS terminology) have a unique name and consist of a linear sequence of lines.