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by stevekemp 337 days ago
It is not necessary to compile a program, in the general case, before executing it.

Many programming languages parse their program to an AST then walk that AST interpretting as they go. But for BASIC you can parse/execute statement by statement - no need to parse the whole program ahead of time, and certainly zero need to compile to either machine code or any internal representation.

Remember at the time we're talking about 64k was a lot of RAM. Some machines had less.
1 comments
WalterBright 337 days ago
The parsing, even if line by line as necessary, is still compiling.
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vidarh 337 days ago
In 45 years of writing software, I've never before seen anyone call tokenizing a BASIC program compilation. It's decidedly not common usage.
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WalterBright 337 days ago
I've been writing compilers for 45 years now. Tokenizing is a big part of every textbook on compilers. To resolve expressions (which are recursive in nature) it would have had to do more than just tokenizing. While this isn't hard at all, it's "parsing" which is also qualifying it as a compiler.

I.e. the basic program was lexing and parsing. It's a compiler. A very simple one, sure, but a compiler.

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vidarh 337 days ago
Yes, but tokenization on its own is not compilation any more than whiskers are a cat just because a cat has them.

"Nobody" uses it that way, and language is defined by use.

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jacquesm 337 days ago
Compilers generate code in another, usually lower level language that is executed by reading all of the code that could be executed first. Interpreters (such as the BASIC interpreter we are discussing here) read only that part of the code that gets executed and typically call functions rather than that they generate code (never mind JIT). Tokenization prior to interpretation is technically an optional step (it's just an efficiency boost) and is not normally confused with compilation even if there are some superficial similarities.

You of all people should know this, come on.

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WalterBright 337 days ago
You and I have a different point of view.
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jacquesm 336 days ago
Of all the hills you could die on this one seems really silly.
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