SYNOPSIS
       lefty [ options ] [ file ]

DESCRIPTION
       lefty is a two-view graphics editor for technical pictures. This editor
       has no hardwired knowledge about specific picture  layouts  or  editing
       operations.  Each picture is described by a program that contains func-
       tions to draw the picture and functions to perform  editing  operations
       that  are appropriate for the specific picture. Primitive user actions,
       like mouse and keyboard events, are also bound  to  functions  in  this
       program.  Besides  the graphical view of the picture itself, the editor
       presents a textual view of the program that describes the picture. Pro-
       grammability  and  the  two-view interface allow the editor to handle a
       variety of pictures, but are particularly useful for pictures  used  in
       technical contexts, e.g., graphs and trees. Also, lefty can communicate
       with other processes. This feature allows it to use existing  tools  to
       compute  specific  picture layouts and allows external processes to use
       the editor as a front end to display their data structures graphically.

USAGE
       The file name is optional. It may  be  -,  for  reading  from  standard
       input.   lefty  uses  two environment variables, LEFTYPATH and LEFTYOP-
       TIONS.  LEFTYPATH is a colon separated list of directories. When  lefty
       tries  to  open  a file, it searches that path for the file. When lefty
       tries to start up another process, it searches  LEFTYPATH  first,  then
       the  standard  PATH variable.  LEFTYOPTIONS can be used to set specific
       options. Options specified on the command  line  override  options  set
       through this variable.

OPTIONS
       -x     Instructs the editor to exit after processing file.

       -e <expression>
              <expression> is parsed and executed.

       -el <num>
              Set  error  reporting  level.  The  default value is 0.  0 never
              prints any messages.  1 prints severe errors, such as trying  to
              return  from  a  non function.  2 is the most useful: it reports
              function calls that cannot be executed, either because there  is
              no  function,  or  because of argument mismatches.  3 also warns
              about bad variable names.  4,5 warn about  expressions  that  do
              not  return  a value. Only level 1 messages are real errors. The
              rest arise from legal lefty statements, but may be cased by some
              logic errors.

       -sd <num>
              Specifies  how  much of the stack to show, when an error message
              is to be printed. The default value is 2.  With 0,  no  part  of
              the stack is shown. With 1, only the top stack frame is printed.
              With 2, the full stack is printed.

       -sb <num>
              Specifies a default file name for postscript files. This name is
              used  when  no  name  is specified in the createwidget call. The
              default file name is out.ps.

       -V     Prints the version.

SEE ALSO
       lefty user guide.