undeclared identifier 'f' if json is imported

[Vindaar]

When trying to build a formula with the f{} macro and importing json at the same time, we'll encounter:

Error: undeclared identifier: 'f'

For instance:

import ggplotnim
import json

let f = f{"Channel" == "Ch 0"}
echo f

This is due to the {} procs exported in json. This is confusing to me, since these are procs and our string / identifier input should never match their signature.

proc `{}`*(node: JsonNode, keys: varargs[string]): JsonNode
proc `{}`*(node: JsonNode, index: varargs[int]): JsonNode

I suppose this is because the implementation for the f{} macro is using the signature:

macro `{}`*(x: untyped{ident}, y: untyped): untyped

where the first arg x is required to be f and y is the actual content of the nnkCurly.

For now as a workaround I'll be adding a fn macro, which expects an nnkCurly argument:

macro `fn`*(x: untyped): untyped =
  let arg = if x.kind == nnkStmtList: x[0] else: x
  expectKind arg, nnkCurly
  ...

which can then be called via:

let f = fn {"Channel" == "Ch 0"} # note the required space!
let f2 = fn({"Channel" == "Ch 0"})
let f3 = fn:
  {"Channel" == "Ch 0"}

In this case the requirement for the curly brackets could of course be removed. I'm not sure which syntax I prefer. If anyone has ideas / an opinion, please let me know!

[Vindaar]

While the related PR is merged, this issue will stay open for the time being, since the underlying issue is not fixed.