Rename/alias :=? operator to :?=

[seigert-xx]

Consider following example:

Json(
  "required" := Option(1) filter (_ > 0),
  "optional" :=? (Option(1)) filter (_ < 0))
)

StringWrap.:= ends with = symbol and thus, according to SLS 6.12.4, has lowest precedence of all infix operators. StringWrap.:=? for Options ends with ? which implies that it is 'normal' infix operator with precedence defined by first : symbol.

: has higher precedence than letters, according to SLS 6.12.3 and that what requires us to put Option(1)) filter (_ < 0) in additional, otherwise unnecessary, brackets.

[markhibberd]

Happy to add the new operator as an alias now, but will leave the other one for now and consider removing it later.

[seigert-xx]

I was wondering also: is it possible to provide some operator (or reuse :=?), which would produce Option[(Json.JsonField, Json)] instance based on 'is right-hand Json is empty or not'?
Example:

("none" ~= jEmptyObject) == None
("some" ~= jSingleObject("test", "value")) == Some(Json("some" := jSingleObject("test", "value")))

[markhibberd]

https://github.com/argonaut-io/argonaut/blob/master/src/main/scala/argonaut/Json.scala#L158

[seigert-xx]

->?: is not of any help here, because we unable to produce Option[JsonAssoc] from jEmptyObject:

scala> import argonaut._, Argonaut._
import argonaut._
import Argonaut._

scala> ("none" :=? jEmptyObject) ->?: jEmptyObject
<console>:14: error: type mismatch;
 found   : argonaut.Json
 required: Option[?]
              ("none" :=? jEmptyObject) ->?: jEmptyObject
                          ^

scala> ("none" := jEmptyObject) ->?: jEmptyObject
<console>:14: error: type mismatch;
 found   : (String, argonaut.Json)
 required: Option[(argonaut.Json.JsonField, argonaut.Json)]
              ("none" := jEmptyObject) ->?: jEmptyObject
                                       ^

[markhibberd]

@seigert This is what you were after in the first instance?

argonaut/src/test/scala/argonaut/StringWrapSpecification.scala

Line 32 in 2e28538

("optional" :?= Some(1) filter (x => x > 0)) must_== Some("optional" := 1)

As for the follow up, the best I can suggest for now is:

def x: Json = ???
("none" :=? x.obj.exists(_.isNotEmpty).option(x)) ->?: jEmptyObject

I will have a think about adding something to do that, but if you really want it can you just throw it in another issue so I can close this one when I release the operator change.

[seigert-xx]

@markhibberd Yep, that's what I meant.

Will move second part to a separate issue.