jorkingit

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I was wondering how they managed to reflect the names of struct fields: looks like https://stackoverflow.com/a/77464529 explains the general idea. Where there's a will, I guess...

jorkingit

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Smalltalk does the same thing!

jorkingit

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Great work! Just an FYI, you might want to limit the dynamic allocation size in the bencode decoder: since it's untrusted input (either from torrent or announce), a malicious input could DoS the client by requesting extremely large allocations during string parsing. A good upper bound could be the remaining length of the input, as a well formed torrent can't contain a string longer than the rest of the file.

jorkingit

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I suspect the answer is 3: SKI combinator calculus is Turing complete and you need 3 de Bruijn indices to define S.

Good call! I got rid of all numbers above 2, I can't count that high anyway ;-)

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I did take some inspiration from Unlambda: the prefix application syntax is cool! I/O in Unlambda is super weird though! You get a read character instruction that puts it into a character register where the only thing you can do is compare it or print it out again; I don't think you can actually do any arithmetic on it.

I'm not sure if I would characterize Brainfuck as a stack language, but I suppose if you considered all the operators to be unary stack operations I could see it!

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https://github.com/imjakingit/lambduck

jorkingit

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I saw this the other day! I salute you, it's so much more evil :-)

And yup, the order of evaluation is leftmost innermost.

  ``\\0`,.`,.

with stdin "hi" will print "hi".

jorkingit

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It should be! e.g. if every function takes a continuation as its final argument, then:

  call/cc& = \f. \k. f k k

Then in f you can invoke the continuation k as many times as you want, but that does involve a whole program transformation to CPS.

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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!

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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.

jorkingit

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Thanks! I'm torn on having the character literals actually; they're definitely syntactical sugar, but I was struggling to write programs that printed anything without them getting super unwieldy! If someone smarter than me can write a compact-looking enough Hello World program then consider them gone ;-)

jorkingit

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Hello world should be:

  ``\\1`.'h``\\1`.'e``\\1`.'l``\\1`.'l``\\1`.'o``\\1`.' ``\\1`.'w``\\1`.'o``\\1`.'r``\\1`.'l``\\1`.'d`.'!

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