json.Marshal can't decode arrays: "invalid key to 'next'" about goluago

[joeytepp]

The following code should work

payload = {
   a_key = array({ 1, 2, 3 })
}

[joeytepp]

Closing this as a solution was found.

[fbogsany]

This happens because we rely on an "array" marker to efficiently identify the table as an array:

goluago/util/deep_pull.go

Lines 56 to 58 in 9f09792

	if isArray(l, idx) {
	return pullArrayRec(l, idx)
	}

[amomchilov]

Thanks Joey, that works.

@fbogsany It looks like this Lua function can detect arrays in O(1), without needing to remember to tag them with a marker:

function is_array(tbl)
  return type(tbl) == 'table' and (#tbl > 0 or next(tbl) == nil)
end

This could be converted to go and be used by the JSON utilities. I'm curious how the performance compares.

The array function call works, but it's not very discoverable.

[fbogsany]

@amomchilov unfortunately, that isn't O(1). The length operator (#tbl in your example) is O(log n) where n is the largest natural key in the table: https://www.lua.org/manual/5.4/manual.html#3.4.7

[amomchilov]

Interesting!

Do you think that might be prohibitively expensive, though I'm not sure.

I wonder if there are anyways to increase the discoverability of the array function.