[jorkingit]

getchar does take a continuation of sorts (as in continuation passing) which is passed the input. In one my initial drafts, getchar was a special form that would accept input at the point of evaluation, which was really funny and unpredictable.

putchar I feel kind of weird about, it acting as an identity function with a side effect is kind of weird; I'm not sure changing it to take a second argument as a continuation would make it better or worse.

Regarding the de Bruijn indices, I don't think there's a huge distinction between writing 3 vs writing ---: it would still form a single lexical token, so I feel like --- is just more noise.

Perhaps a de Bruijn index register you could move around and dereference? e.g. from index 1, index 3 is >>*, then index 2 from there is <*. But that feels less functional, because you're now imperatively manipulating some hidden state.

[fc417fc802]

Entirely agreed that it's nothing but more noise, but isn't that exactly how BF is? Why ----- instead of 5-? Well, because BF of course. The point of the exercise (IMO) is having the bare minimum in parsed characters to achieve the turing tarpit.

I quite like the movable register idea but as you say that's no longer a "BF except lambda calculus" it's some other esolang at that point.

I think my objection about the lack of continuations was misplaced given that appears to be a BF take on the lambda calculus rather than a BF take on scheme.

[jorkingit]

You can always write it in continuation-passing style if you really want continuations! It's not pleasant but none of this is supposed to be ;-)

Agreed on having too many characters though, I don't like that having numerical indices makes the syntax whitespace-sensitive, too.

And once I figure out how to write hello world, those character literals are gone!