The Compiler/Lister

Before PRO/5 can execute a command, the command must first be converted into an internal coded form. The compiler does this automatically when you type a line. This internal format allows for more compact programs and faster execution. An error message is displayed if the compiler is unable to compile a line, because of syntax errors or insufficient memory. For example, if the error is a syntax error and the line is prefixed with a line number, the line is stored in the program exactly as typed, but flagged to indicate that it is invalid. Any attempt to execute the line before correcting it will cause an error message.

When typing in a line, observe the following:

• All lower-case letters that do not appear inside of quotation marks will be internally converted to upper case. This allows for case insensitive command lines.

• The names of certain commands and functions consist of several characters together such as GOTO. For example, GO TO would not be recognized by the compiler because of an embedded space between GO and TO.

• The elements of a command must be separated by spaces. For example:

Correct	Incorrect
PRINT A	PRINTA
GOTO 1000	GOTO1000

The lister converts a line from its internal, compiled form into a form you can read. This is done when you execute the LIST verb. The LISTed form of a line might not look identical to what was originally typed. PRO/5 removes redundant spaces from lines when they are compiled.