GW-BASIC | The original source code of Microsoft GW-BASIC

I'm surprised that the first bascom you found reported an error. All compilers that I've ever used for BASIC, and I believe I've used a lot of them since 1982 on, made line numbers optional and supported labels. I remember that in my first job as a professional programmer, we designed a compiler pre-processor that would insert only lines needed for proper IF, ELSE IF and END IF statements by replacing stuff with line numbers and (gasp) GOTO statements.

I still use line numbers today in my still supported VB6 accounting application thanks to MZ-Tools add-in that allows me to add and remove line numbers to my methods and function with a single button click. This allows me to use Erl (error line number) in all my error routines, also a quick one-button add to all my methods and functions, which allows me to pin-point the exact line any error occurs on.

I'm sure the compiler designers thought that line numbers were only of real use to interpreters, and perhaps the first version of bascom figured you'd develop and test with an interpreter, then compile and distribute the executable, then perhaps later versions figured developers were using text editors, especially the later versions that came with their own IDE's and who would need line numbers there? Well, we do if we want precise error reporting! That's one thing I like about Java and Eclipse. The line numbers are there so I can know exactly where the errors are, but they don't get in the way like they do in BASIC (remove line numbers, add/remove code, replace line numbers).

What I'm wondering is whether that first "argument" ever used for anything prior to GW-BASIC, i.e. something like this was actually useful:

Using PRINT with a semicolon will not print a new line: