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3 points by tokipin 6128 days ago | link | parent

the nice thing about using multiple newlines as markers for new forms is we don't have to worry about indentation

those examples i gave for exterior symbols are just to show the sorts of things that could be possible. the 4 * notation for example would be completely out of place in Arc. (it's a notation that one of my LOGO languages uses.) the only example of those that i think is nifty is the | notation

though that piping could have some interesting uses. basically it lets you write functional statements in directed form rather than nested

  (def a (x) (+ x 1))
  (def b (x) (* x 2))
  
  ((a => b) 3)       ->       ((fn (x) (* (+ x 1) 2)) 3)

  3 => + <= 2   ->   5 or [+ 5 _]

  a b => + => [* _ 3] => [/ 1 _] => sqrt    ->   (fn (a b)
                                                     (sqrt (/ 1 (* (+ a b) 3))))
with the "implied underscore" form of [...]:

  a b => + => [* 3] => [/ 1] => sqrt

  sqrt <= [/ 1] <= [* 3] <= + <= a b
args within nodes:

  a => [* 3] b => +      ->     (fn (a b)
                                    (+ (* a 3) b))
so it's basically composition with some things to make it more general

i wonder what tomfoolery could be done by using the list as the format for the directed graph

anyways, i don't really know what i'm talking about wrt piping, and i don't find the notation very handsome. though it just occured to me that we can already just make a 'pipe' macro/function that would allow us to write things close enough to that notation. programmable programming language indubitably

and again, these are just heuristics for the most part. maybe with the small spark of these examples, other people can come up with some useful notations, or more useful sparks that may eventually lead to some :)



3 points by eds 6127 days ago | link

Oh, I didn't see your note about multiple newlines separating forms. That is an interesting approach, and removes the need for meaningful whitespace. But I have to wonder if it might get a little tiresome at the repl, since you would always have to add an extra newline to all your one line forms (unless you reverted to outer parens again).

And I now see what piping does, although I agree with you that the notation doesn't look very nice.

Perhaps external symbols could be used to do infix math? Although that might make it difficult to distinguish from when you want to do (for example):

  (map + '(1 2 3) '(4 5 6))

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2 points by tokipin 6127 days ago | link

yea for the REPL i'm not exactly sure. i think it would have to be limited to 1-liners. for multiple lines then you'd have to use outer parens. where it would get wack is, say, copy & pasting code into the REPL, and if that code isn't using outer parens, how would it be parsed? it wouldn't be a problem if it was pasted and read in a 'chunk', but i think in my console it's pasted line-by-line or parsed line-by-line as if manually input. i'm not sure. hmmm. we might have to say "use outer parens if you're going to paste the code into the REPL"

however, that's the behavior as it is now in the scheme REPL. a custom Arc REPL would be able to handle things like pastes appropriately (maybe. i'm not familiar with console mechanics, but even if it wasn't 'purely' possible, a timer could be used so that if the delta between the last and currently entered lines is less than X, then it would be safe to assume the sequence was pasted)

for infix math it might be best to have a marker that says "the following form is infix"

  #( (3 + 2) / 8 )     ->     (/ (+ 3 2) 8 )
some other thoughts are notations for pattern matching/RE's

  @([aA][rR][cC])

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5 points by eds 6127 days ago | link

I'm really uncomfortable about making the repl and file readers differ, especially to the point of being incompatible.

About a custom console, I am not sure there is any reliable way to detect when a user has pasted code into the console. (That sort of thing is probably very OS dependent.)

Even if you did set up a timer like you propose, what would it do if the user recalled some lines from a multiline entry in history? I think most consoles would only pull up one line of history at a time, so the user would have to go through each line and enter it individually. And the timing would be such as to be indistinguishable from direct input from the user.

As for infix math, if you created an infix marker like

  #( (3 + 2) / 8 )
then you really aren't saving anything over

  (# (3 + 2) / 8)
at which point you could just use a macro.

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1 point by tokipin 6127 days ago | link

yea that's true. i'm new to lisp so a lot of these things don't occur to me right away (well, that's my excuse at least)

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2 points by Jesin 6112 days ago | link

What happens if you want to interpolate @([aA][rR][cC]) into a quasiquote?

  (foo ,@([aA][rR][cC]) ,baz)
See the problem?

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0 points by Jesin 6112 days ago | link

What happens if you want to interpolate @([aA][rR][cC]) into a quasiquote?

  (foo ,@([aA][rR][cC]) ,baz)
See the problem?

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