What this article boils down to is two things: 1) Computers used to have a built-in language that would be immediately available, and 2) that language had a REP

What this article boils down to is two things: 1) Computers used to have a built-in language that would be immediately available, and 2) that language had a REPL. If you wanted to get the same experience in any REPL without line numbers (and with Lambdas), you could say: mainprog = lambda{some lines of code}; exec mainprog; instead of: 10 line 1 of code 20 line 2 of code RUN In the case of BASIC, prefixing a line number is a shortcut for saying "variable LINE-XX = lambda{some code}". Now we just need to get computers to come up with a standardized REPL readily available at boot time. Maybe if web browsers started to default to having a Javascript console prominently displayed at all times.