Add hidden field

[CristhianMotoche]

Solves #2

Changes

• Add Hidded, which is a new constructor for KeyValue
• Ignoring any Hidden attribute by returning (VNull, undefined)
• undefined won't be evaluated because its filtered from the KeyValue list

Please, let me know if this would solve the issue. 😃

[moleike]

Hi Cristhian, thanks for your patch! I am reviewing this later 👍

[moleike]

Very impressive work!
Please see my comments in the code. Also:

• You might change the evalObj method to account for hidden fields, then in the VObj constructor change the keys from Text to a new type, e.g. data Key = Visible Text | Hidden Text the idea here is that fields should all be usable, the only time we care about whether it's a hidden field is when:
  • materializing an object (Value -> JSON), where hidden fields are filtered out
  • checking equality, again hidden fields are just ignored.

Also, keep in mind this is unrelated to private/public fields.

If this is not clear, please let me know!

[moleike]

Methods can be hidden too, but here it would fail to parse { foo :: function(x) x }.
Here I would suggest changing the result to KeyValue key value hidden, where hidden is derived from paring either symbol : or ::.

[moleike]

Hidden fields, also have values, e.g.

{ foo : "bar", baz(x) :: x + 1 }

In this case, you might use the baz method in the program, regardless of the object being serialized to JSON.

As an example, the functions in the standard library are all hidden fields of the std object (https://jsonnet.org/ref/stdlib.html)

[moleike]

My suggestion here would be to add an additional field hidden :: Bool to the KeyValue constructor.

[CristhianMotoche]

Thanks for the suggestions @moleike I'll review them later today.

[CristhianMotoche]

Hi @moleike I tried your approach but I got stuck with this type error:

...l/jsonnet-haskell/src/Language/Jsonnet/Std.hs:42:26: error:
    • No instance for (Integral Key) arising from a use of ‘inj’
    • In the expression: inj (H.keys @Key @Value)
      In the expression: ("objectFields", inj (H.keys @Key @Value))
      In the expression:
        [("assertEqual", inj assertEqual), ("type", inj valueType),
         ("isString", inj (isType "string")),
         ("isBoolean", inj (isType "boolean")), ....]
   |
42 |         ("objectFields", inj (H.keys @Key @Value)),

Please, let me know if I'm going in the right direction or I lost at some point. I understood that manifest makes the final conversion of Value to JSON and it's used in toString and equalTo. Therefore, I should filter the visible keys there.

[CristhianMotoche]

I managed to fix the error type, but I'm not sure about my implementation.

[moleike]

Hi @CristhianMotoche, the problem you encounter is due to the impl. of objectFields method. So you don't need an HasValue instance for Key:

diff --git a/src/Language/Jsonnet/Eval.hs b/src/Language/Jsonnet/Eval.hs
index 8dc0428..d0c0993 100644
--- a/src/Language/Jsonnet/Eval.hs
+++ b/src/Language/Jsonnet/Eval.hs
@@ -124,10 +124,6 @@ instance HasValue Double where
   proj v = throwTypeMismatch "number" v
   inj = VNum
 
-instance HasValue Key where
-  proj = undefined
-  inj = undefined
-
 instance {-# OVERLAPS #-} Integral a => HasValue a where
   proj (VNum n) = pure (round n)
   proj v = throwTypeMismatch "number" v
diff --git a/src/Language/Jsonnet/Std.hs b/src/Language/Jsonnet/Std.hs
index ba2a1d3..2f8d67a 100644
--- a/src/Language/Jsonnet/Std.hs
+++ b/src/Language/Jsonnet/Std.hs
@@ -9,6 +9,7 @@ import Control.Applicative
 import Control.Monad.Except
 import qualified Data.ByteString as B
 import Data.Foldable
+import Data.HashMap.Lazy (HashMap)
 import qualified Data.HashMap.Lazy as H
 import Data.List
 import Data.Text (Text)
@@ -39,7 +40,7 @@ std = VObj $ (Thunk . pure) <$> H.fromList (map (\(k, v) -> (Visible k, v)) xs)
         ("isObject", inj (isType "object")),
         ("isArray", inj (isType "array")),
         ("isFunction", inj (isType "function")),
-        ("objectFields", inj (H.keys @Key @Value)),
+        ("objectFields", inj objectFields),
         ("length", inj length'),
         ("abs", inj (abs @Double)),
         ("sign", inj (signum @Double)), -- incl. 0.0, (-0.0), and NaN
@@ -98,6 +99,10 @@ std = VObj $ (Thunk . pure) <$> H.fromList (map (\(k, v) -> (Visible k, v)) xs)
         ("reverse", inj (reverse @Value))
       ]
 
+
+objectFields :: HashMap Key Value -> [Text]
+objectFields o = [k | Visible k <- H.keys o]
+
 assertEqual :: Value -> Value -> Eval Bool
 assertEqual a b = do
   a' <- manifest a

[moleike]

I understood that manifest makes the final conversion of Value to JSON and it's used in toString and equalTo. Therefore, I should filter the visible keys there.

That's correct.

Please, let me know if I'm going in the right direction

Yes you are 👍

[CristhianMotoche]

Thank you so much for you kind guidance @moleike Let me know if you have any other comment/suggestion. 😃

[moleike]

@CristhianMotoche I think the issue is solved with your changes. Congrats on tackling this issue!

[moleike]

LGTM

[moleike]

There's one minor issue remaining, but it can be fixed later on:
The parses will fail to parse { foo(x) :: x }, which is sugar for { foo :: function(x) x }.