[munificent]

> Interestingly, Tcl was parsed the same way all the way up until Tcl 8.0 introduced a bytecode system in 1997. Each line was parsed right before execution with no separate parsing stage--your code could crash in the middle of executing from a syntax error.

Fun fact: most modern JavaScript engines in browsers work this way today, though at a different level of granularity. Parsing slows down application startup, so many JS engines don't parse a function body until it's first called. This means you can have a syntax error in a function body and won't know if it's never used.

[normac]

That's pretty neat. Clearly some level of parsing needs to happen before run time, or else it couldn't even balance braces to know where the function body ends. So it must be that it parses the function body just enough to figure out where it starts and ends, then does a complete parse at runtime (probably building off the results from the first stage).

[munificent]

> or else it couldn't even balance braces to know where the function body ends

That's literally all it does. It tokenizes and counts braces.