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Retrocomputing

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    Very interesting. Someday I'll have to figure out how they did that... normally an interpreter wouldn't know where to go if the test fails immediately, so either they do a lookahead or they top test and then roll forward to the NEXT instead of the other way around. Commented Apr 23, 2022 at 20:23
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    @MauryMarkowitz - I don't see why being an interpreter prevents a scan over the source code before execution starts. Commented Apr 23, 2022 at 22:12
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    @MauryMarkowitz: there's also no requirement to scan up front. You could do something like have a flag indicating "I'm in a dead for loop" which reads but doesn't execute code. You stay in that mode until you get to the corresponding NEXT (so you'll probably need to stack dead FOR/NEXT pairs) then turn off the flag. Not how I would do it, I'd prefer pre-scan to speed things up. Commented Apr 23, 2022 at 23:50
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    I understand the hesitation, but finding the closest NEXT forward shouldn’t be fundamentally harder than implementing GOTO to a forward line number. Commented Apr 24, 2022 at 0:12
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    @paxdiablo: "When the value of the simple variable passes the final value": the initial value has already passed the final value if N=0, so the loop is never entered. Commented Apr 24, 2022 at 2:22