The CIRCLED Dialect: Example of the Form

I was looking at this from the emscripten config file:

 ; Right now, either #web or #node (someday #wasm-edge ?)
 ;
 javascript-environment: #web

And I thought to myself: well that's kind of ugly. The comment is having to list things that would be more obviously shown by just demonstrating the options:

javascript-environment: circled [(#web) #node]

Being dialected, it could even have visual hints as to whether many options are allowed, or just one.

extensions: circled [[
   (javascript)
   (debugger)
    view
    jpeg
   (crypto)
]]

Or maybe it uses optional parameters to tell you how many you can have.

toppings: circled 0..3 [(cheese) tomatoes (pickles) (lettuce) onions]

It could default to NULL if you circled nothing, but you could use MUST to suggest people needed to select something:

>> number: must circled [#one #two #three]
** Error: MUST requires argument not to be NULL

It's Almost Too Easy

When it's this easy, who wouldn't whip such things up?

Ultimately I believe this should work (once PARSE is renamed and there's Terminal Parse Alternates):

circled: lambda [block [block!]] [
    parse block [return [
         thru into group! [<any> | (fail "Circle One")]
         maybe [thru group! (fail "Circle One")]
    ]]
]

>> circled [a (b) c]
== b

>> circled [a b c]
; null

>> circled [(a) b (c)]
** Error: Circle One

>> circled [a (b c)]
** Error: Circle One

But of course PARSE is called UPARSE right now, and there's a detail of alternates not being offered in blocks seeking completion before failing...that makes you need elide <end>, so for now:

circled: lambda [block [block!]] [
    uparse block [return [
         thru into group! [<any> elide <end> | (fail "Circle One")]
         maybe [thru group! (fail "Circle One")]
    ]]
]

It finds one group to extract an element from, and extracts it via INTO. Then it has a second clause that's optional--and if it doesn't match is invisible...but if it does match it fails.

Remarkable plasticity, and I want to see these weapons come to the code golfing field. :slight_smile:

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