Add JSON.field to prelude

[SiriusStarr]

JSON.field is a helper function for making JSON.object entries, a simple convenience that helps with constructing basically any JSON in Dhall. This function is in every JSON interface I've made in Dhall and seems reasonable for inclusion in the prelude.

Since the map value is always JSON.Type for JSON objects, it's more convenient to have this function that having to write JSON.keyValue JSON.Type every single time you construct a field for an object (or to write out the map entry by hand).

For example, the basic example object goes from

let JSON = ./package.dhall

in  JSON.render
      ( JSON.object
          [ { mapKey = "foo", mapValue = JSON.double 1.0 }
          , { mapKey = "bar", mapValue = JSON.bool True }
          ]
      )

to

let JSON = ./package.dhall

in  JSON.render
      ( JSON.object
          [ JSON.field "foo" (JSON.double 1.0)
          , JSON.field "bar" (JSON.bool True)
          ]
      )

with this new function.

[Gabriella439]

It might be worth mentioning in this documentation that another alternative for people interested in this is to use toMap:

let JSON = ./package.dhall

in  JSON.render
      ( JSON.object
          ( toMap
              { foo = JSON.double 1.0
              , bar = JSON.bool True
              }
          )
      )

[SiriusStarr]

I am...not smart and completely forgot the toMap builtin existed. In light of that, do you still think JSON.field is a useful addition, or just clutter in the Prelude?

[Gabriella439]

@SiriusStarr: In that case, maybe we don't need the JSON.field utility, or at least wait to see if somebody requests it even knowing about toMap

[philandstuff]

I have previously written a similar utility which takes an `Optional x` and provides a JSON map entry in a list of length one if present, or an empty list if absent. Then these optional entries can be pasted together with `#` (using `toMap` for the non-optional entries).

…

On Mon, 8 Mar 2021 at 05:12, Gabriel Gonzalez ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In Prelude/JSON/field.dhall <#1143 (comment)> : > @@ -0,0 +1,27 @@ +{-| +Create a JSON field for a JSON object from a Dhall `Text` key and a JSON value @SiriusStarr <https://github.com/SiriusStarr>: In that case, maybe we don't need the JSON.field utility, or at least wait to see if somebody requests it even knowing about toMap — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1143 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEN5FNUV4ZWYGYQITKTK43TCRMFBANCNFSM4YV7ASNA> .

[SiriusStarr]

I have previously written a similar utility which takes an Optional x and
provides a JSON map entry in a list of length one if present, or an empty
list if absent. Then these optional entries can be pasted together with #
(using toMap for the non-optional entries).

(Having done the same previously) this might honestly be a better prelude inclusion than field, since there's little reason to not just use toMap for non-optionals, but that doesn't work for fields you want to optionally exclude.