add json

JSON/Format.dhall

@@ -0,0 +1,7 @@
+{-|
+An internal type used by `./renderAs` to select the output format.
+
+You should not need to use this type directly, simply use `./render`
+or `./renderYAML` as appropriate.
+-}
+< YAML | JSON >

JSON/Nesting.dhall

@@ -0,0 +1,35 @@
+{-|
+This type is used as part of `dhall-json`'s support for preserving alternative
+names
+
+For example, this Dhall code:
+
+```
+let Example = < Left : { foo : Natural } | Right : { bar : Bool } >
+
+let Nesting = < Inline | Nested : Text >
+
+in  { field =
+        "name"
+    , nesting =
+        Nesting.Inline
+    , contents =
+        Example.Left { foo = 2 }
+    }
+```
+
+... generates this JSON:
+
+```
+{
+  "foo": 2,
+  "name": "Left"
+}
+```
+
+-}
+let Nesting
+    : Type
+    = < Inline | Nested : Text >
+
+in  Nesting

JSON/Tagged.dhall

@@ -0,0 +1,67 @@
+{-|
+This is a convenient type-level function when using `dhall-to-json`'s support
+for preserving alternative names
+
+For example, this code:
+
+```
+let map = ../List/map
+
+let Provisioner =
+      < shell :
+          { inline : List Text }
+      | file :
+          { source : Text, destination : Text }
+      >
+
+let Tagged = ./Tagged
+
+let Nesting = ./Nesting
+
+let wrap
+    : Provisioner → Tagged Provisioner
+    = λ(x : Provisioner) →
+        { field = "type", nesting = Nesting.Nested "params", contents = x }
+
+in  { provisioners =
+        map
+        Provisioner
+        (Tagged Provisioner)
+        wrap
+        [ Provisioner.shell { inline = [ "echo foo" ] }
+        , Provisioner.file
+          { source = "app.tar.gz", destination = "/tmp/app.tar.gz" }
+        ]
+    }
+```
+
+... produces this JSON:
+
+```
+{
+  "provisioners": [
+    {
+      "params": {
+        "inline": [
+          "echo foo"
+        ]
+      },
+      "type": "shell"
+    },
+    {
+      "params": {
+        "destination": "/tmp/app.tar.gz",
+        "source": "app.tar.gz"
+      },
+      "type": "file"
+    }
+  ]
+}
+```
+
+-}
+let Tagged
+    : Type → Type
+    = λ(a : Type) → { field : Text, nesting : ./Nesting.dhall, contents : a }
+
+in  Tagged

JSON/Type.dhall

@@ -0,0 +1,63 @@
+{-|
+Dhall encoding of an arbitrary JSON value
+
+For example, the following JSON value:
+
+```
+[ { "foo": null, "bar": [ 1.0, true ] } ]
+```
+
+... corresponds to the following Dhall expression:
+
+```
+λ(JSON : Type) →
+λ ( json
+  : { array : List JSON → JSON
+    , bool : Bool → JSON
+    , null : JSON
+    , double : Double → JSON
+    , integer : Integer → JSON
+    , object : List { mapKey : Text, mapValue : JSON } → JSON
+    , string : Text → JSON
+    }
+  ) →
+  json.object
+    [ { mapKey = "foo", mapValue = json.null }
+    , { mapKey = "bar"
+      , mapValue = json.array [ json.double 1.0, json.bool True ]
+      }
+    ]
+```
+
+  You do not need to create these values directly, though.  You can use
+  the utilities exported by `./package.dhall` to create values of this type,
+  such as:
+
+```
+let JSON = ./package.dhall
+
+in  JSON.object
+      [ { mapKey = "foo", mapValue = JSON.null }
+      , { mapKey = "bar"
+        , mapValue = JSON.array [ JSON.double 1.0, JSON.bool True ]
+        }
+      ]
+```
+
+-}
+let JSON/Type
+    : Type
+    = ∀(JSON : Type) →
+      ∀ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        JSON
+
+in  JSON/Type

JSON/array.dhall

@@ -0,0 +1,35 @@
+{-|
+Create a JSON array from a `List` of JSON values
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.array [ JSON.double 1.0, JSON.bool True ])
+= "[ 1.0, true ]"
+
+let JSON/Type = ./Type
+let JSON = ./package.dhall
+in  JSON.render (JSON.array ([] : List JSON/Type))
+= "[ ]"
+```
+-}
+let JSON = ./Type.dhall
+
+let List/map = ../List/map.dhall
+
+let array
+    : List JSON → JSON
+    = λ(x : List JSON) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.array (List/map JSON@1 JSON (λ(j : JSON@1) → j JSON json) x)
+
+in  array

JSON/bool.dhall

@@ -0,0 +1,32 @@
+{-|
+Create a JSON bool from a Dhall `Bool`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.bool True)
+= "true"
+
+let JSON = ./package.dhall
+in  JSON.render (JSON.bool False)
+= "false"
+```
+-}
+let JSON = ./Type.dhall
+
+let bool
+    : Bool → JSON
+    = λ(x : Bool) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.bool x
+
+in  bool

JSON/core.dhall

@@ -0,0 +1,25 @@
+{-|
+A record of functions useful for constructing `JSON` values.
+
+This is only a subset of what `package.dhall` exports. If you are not writing a
+JSON prelude function, you should use the `package.dhall` file instead.
+
+It is used internally by `render`, `renderYAML` and `omitNullFields` instead of
+`package.dhall` to avoid import cycles.
+-}
+{ Type = ./Type.dhall
+, Tagged = ./Tagged.dhall
+, Nesting = ./Nesting.dhall
+, keyText = ./keyText.dhall
+, keyValue = ./keyValue.dhall
+, string = ./string.dhall
+, number = ./number.dhall
+, double = ./double.dhall
+, integer = ./integer.dhall
+, natural = ./natural.dhall
+, object = ./object.dhall
+, array = ./array.dhall
+, bool = ./bool.dhall
+, null = ./null.dhall
+, renderInteger = ./renderInteger.dhall
+}

JSON/double.dhall

@@ -0,0 +1,32 @@
+{-|
+Create a JSON number from a Dhall `Double`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.double 42.0)
+= "42.0"
+
+let JSON = ./package.dhall
+in  JSON.render (JSON.double -1.5e-10)
+= "-1.5e-10"
+```
+-}
+let JSON = ./Type.dhall
+
+let double
+    : Double → JSON
+    = λ(x : Double) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.double x
+
+in  double

JSON/integer.dhall

@@ -0,0 +1,32 @@
+{-|
+Create a JSON number from a Dhall `Integer`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.integer -1)
+= "-1"
+
+let JSON = ./package.dhall
+in  JSON.render (JSON.integer +2)
+= "+2"
+```
+-}
+let JSON = ./Type.dhall
+
+let integer
+    : Integer → JSON
+    = λ(x : Integer) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.integer x
+
+in  integer

JSON/keyText.dhall

@@ -0,0 +1 @@
+../Map/keyText.dhall

JSON/keyValue.dhall

@@ -0,0 +1 @@
+../Map/keyValue.dhall

JSON/natural.dhall

@@ -0,0 +1,28 @@
+{-|
+Create a JSON number from a Dhall `Natural`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.natural 42)
+= "42"
+```
+-}
+let JSON = ./Type.dhall
+
+let natural
+    : Natural → JSON
+    = λ(x : Natural) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.integer (Natural/toInteger x)
+
+in  natural

JSON/null.dhall

@@ -0,0 +1,27 @@
+{-|
+Create a JSON null
+
+```
+let JSON = ./package.dhall
+in  JSON.render JSON.null
+= "null"
+```
+-}
+let JSON = ./Type.dhall
+
+let null
+    : JSON
+    = λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.null
+
+in  null

JSON/number.dhall

@@ -0,0 +1,22 @@
+{-|
+Create a JSON number from a Dhall `Double`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.number 42.0)
+= "42.0"
+
+let JSON = ./package.dhall
+in  JSON.render (JSON.number -1.5e-10)
+= "-1.5e-10"
+```
+-}
+let JSON = ./Type.dhall
+
+let double = ./double.dhall
+
+let number
+    : Double → JSON
+    = double
+
+in  number

JSON/object.dhall

@@ -0,0 +1,49 @@
+{-|
+Create a JSON object from a Dhall `Map`
+
+```
+let JSON = ./package.dhall
+in  JSON.render
+    ( JSON.object
+      [ { mapKey = "foo", mapValue = JSON.double 1.0 }
+      , { mapKey = "bar", mapValue = JSON.bool True  }
+      ]
+    )
+= "{ \"foo\": 1.0, \"bar\": true }"
+
+let JSON/Type = ./Type
+let JSON = ./package.dhall
+in  JSON.render
+    (JSON.object ([] : List { mapKey : Text, mapValue : JSON/Type }))
+= "{ }"
+```
+-}
+let JSON = ./Type.dhall
+
+let List/map = ../List/map.dhall
+
+let object
+    : List { mapKey : Text, mapValue : JSON } → JSON
+    = λ(x : List { mapKey : Text, mapValue : JSON }) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.object
+          ( List/map
+              { mapKey : Text, mapValue : JSON@1 }
+              { mapKey : Text, mapValue : JSON }
+              ( λ(kv : { mapKey : Text, mapValue : JSON@1 }) →
+                  { mapKey = kv.mapKey, mapValue = kv.mapValue JSON json }
+              )
+              x
+          )
+
+in  object

JSON/omitNullFields.dhall

@@ -0,0 +1,136 @@
+{-|
+This utility omits all `null` record fields, which is often the idiomatic way
+for a configuration to encode absent fields
+-}
+let JSON = ./core.dhall
+
+let List/concatMap = ../List/concatMap.dhall
+
+let List/map = ../List/map.dhall
+
+let omitNullFields
+    : JSON.Type → JSON.Type
+    = λ(old : JSON.Type) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        let result =
+              old
+                { value : JSON, isNull : Bool }
+                { string =
+                    λ(x : Text) → { value = json.string x, isNull = False }
+                , double =
+                    λ(x : Double) → { value = json.double x, isNull = False }
+                , integer =
+                    λ(x : Integer) → { value = json.integer x, isNull = False }
+                , object =
+                    λ ( keyValues
+                      : List
+                          { mapKey : Text
+                          , mapValue : { value : JSON, isNull : Bool }
+                          }
+                      ) →
+                      let value =
+                            json.object
+                              ( List/concatMap
+                                  { mapKey : Text
+                                  , mapValue : { value : JSON, isNull : Bool }
+                                  }
+                                  { mapKey : Text, mapValue : JSON }
+                                  ( λ ( keyValue
+                                      : { mapKey : Text
+                                        , mapValue :
+                                            { value : JSON, isNull : Bool }
+                                        }
+                                      ) →
+                                      if    keyValue.mapValue.isNull
+                                      then  [] : List
+                                                   { mapKey : Text
+                                                   , mapValue : JSON
+                                                   }
+                                      else  [   keyValue.{ mapKey }
+                                              ∧ { mapValue =
+                                                    keyValue.mapValue.value
+                                                }
+                                            ]
+                                  )
+                                  keyValues
+                              )
+
+                      in  { value, isNull = False }
+                , array =
+                    λ(xs : List { value : JSON, isNull : Bool }) →
+                      let value =
+                            json.array
+                              ( List/map
+                                  { value : JSON, isNull : Bool }
+                                  JSON
+                                  ( λ(x : { value : JSON, isNull : Bool }) →
+                                      x.value
+                                  )
+                                  xs
+                              )
+
+                      in  { value, isNull = False }
+                , bool = λ(x : Bool) → { value = json.bool x, isNull = False }
+                , null = { value = json.null, isNull = True }
+                }
+
+        in  result.value
+
+let property =
+      λ(a : Text) →
+      λ(b : Double) →
+      λ(c : Bool) →
+          assert
+        :   omitNullFields
+              ( JSON.object
+                  ( toMap
+                      { string = JSON.string a
+                      , double = JSON.double b
+                      , bool = JSON.bool c
+                      , null = JSON.null
+                      }
+                  )
+              )
+          ≡ JSON.object
+              ( toMap
+                  { string = JSON.string a
+                  , double = JSON.double b
+                  , bool = JSON.bool c
+                  }
+              )
+
+let example =
+        assert
+      :   omitNullFields
+            ( JSON.object
+                ( toMap
+                    { array =
+                        JSON.array [ JSON.object (toMap { null = JSON.null }) ]
+                    }
+                )
+            )
+        ≡ JSON.object
+            ( toMap
+                { array =
+                    JSON.array
+                      [ JSON.object
+                          ([] : List { mapKey : Text, mapValue : JSON.Type })
+                      ]
+                }
+            )
+
+let example =
+        assert
+      : omitNullFields (JSON.array [ JSON.null ]) ≡ JSON.array [ JSON.null ]
+
+in  omitNullFields

JSON/package.dhall

@@ -0,0 +1,9 @@
+λ(nix : ../NixPrelude.dhall) →
+    { render = ./render.dhall nix
+    , renderCompact = ./renderCompact.dhall
+    , renderYAML = ./renderYAML.dhall nix
+    , omitNullFields = ./omitNullFields.dhall
+    , tagInline = ./tagInline.dhall
+    , tagNested = ./tagNested.dhall
+    }
+  ∧ ./core.dhall

JSON/render.dhall

@@ -0,0 +1,12 @@
+λ(nix : ../NixPrelude.dhall) →
+  let JSON = ./core.dhall
+
+  let Format = ./Format.dhall
+
+  let renderAs = ./renderAs.dhall nix
+
+  let render
+      : JSON.Type → Text
+      = renderAs Format.JSON
+
+  in  render

JSON/renderAs.dhall

@@ -0,0 +1,298 @@
+--| Render a `JSON` value as `Text` in either JSON or YAML format.
+λ(nix : ../NixPrelude.dhall) →
+  let JSON = ./core.dhall
+
+  let Function/identity = ../Function/identity.dhall
+
+  let Text/concatMap = ../Text/concatMap.dhall
+
+  let List/map = ../List/map.dhall
+
+  let NonEmpty = ../NonEmpty/Type.dhall
+
+  let NonEmpty/toList = ../NonEmpty/toList.dhall
+
+  let NonEmpty/concat = ../NonEmpty/concat.dhall
+
+  let NonEmpty/map = ../NonEmpty/map.dhall
+
+  let NonEmpty/singleton = ../NonEmpty/singleton.dhall
+
+  let Optional/fold = ../Optional/fold.dhall nix
+
+  let List/uncons
+      : ∀(a : Type) → List a → Optional (NonEmpty a)
+      = {- This version uses the `ls` argument only once to prevent cache blowups at the price
+           of performing two passes over the list:
+           A first one to reverse it, a second one with `List/fold` to determine
+           the head element.
+           See https://github.com/dhall-lang/dhall-lang/pull/1015#issuecomment-633381024
+           for some context regarding the caching issue.
+        -}
+        λ(a : Type) →
+        λ(ls : List a) →
+          List/fold
+            a
+            (List/reverse a ls)
+            (Optional (NonEmpty a))
+            ( λ(x : a) →
+              λ(acc : Optional (NonEmpty a)) →
+                Optional/fold
+                  (NonEmpty a)
+                  acc
+                  (Optional (NonEmpty a))
+                  (λ(ne : NonEmpty a) → Some (ne ⫽ { tail = ne.tail # [ x ] }))
+                  (Some (NonEmpty/singleton a x))
+            )
+            (None (NonEmpty a))
+
+  let NonEmpty/mapHead
+      : ∀(a : Type) → (a → a) → NonEmpty a → NonEmpty a
+      = λ(a : Type) →
+        λ(fn : a → a) →
+        λ(ls : NonEmpty a) →
+          ls ⫽ { head = fn ls.head }
+
+  let NonEmpty/mapTail
+      : ∀(a : Type) → (a → a) → NonEmpty a → NonEmpty a
+      = λ(a : Type) →
+        λ(fn : a → a) →
+        λ(ls : NonEmpty a) →
+          ls ⫽ { tail = List/map a a fn ls.tail }
+
+  let NonEmpty/prepend
+      : ∀(a : Type) → a → NonEmpty a → NonEmpty a
+      = λ(a : Type) →
+        λ(prefix : a) →
+        λ(ls : NonEmpty a) →
+          { head = prefix, tail = NonEmpty/toList a ls }
+
+  let NonYtpme
+      : Type → Type
+      = λ(a : Type) → { init : List a, last : a }
+
+  let List/unsnoc
+      : ∀(a : Type) → List a → Optional (NonYtpme a)
+      = λ(a : Type) →
+        λ(ls : List a) →
+          List/fold
+            a
+            ls
+            (Optional (NonYtpme a))
+            ( λ(x : a) →
+              λ(acc : Optional (NonYtpme a)) →
+                Optional/fold
+                  (NonYtpme a)
+                  acc
+                  (Optional (NonYtpme a))
+                  (λ(ny : NonYtpme a) → Some (ny ⫽ { init = [ x ] # ny.init }))
+                  (Some { init = [] : List a, last = x })
+            )
+            (None (NonYtpme a))
+
+  let NonEmpty/mapLast
+      : ∀(a : Type) → (a → a) → NonEmpty a → NonEmpty a
+      = λ(a : Type) →
+        λ(fn : a → a) →
+        λ(ls : NonEmpty a) →
+          Optional/fold
+            (NonYtpme a)
+            (List/unsnoc a ls.tail)
+            (NonEmpty a)
+            (λ(x : NonYtpme a) → ls ⫽ { tail = x.init # [ fn x.last ] })
+            (NonEmpty/singleton a (fn ls.head))
+
+  let NonEmpty/mapLeading
+      : ∀(a : Type) → (a → a) → NonEmpty a → NonEmpty a
+      = λ(a : Type) →
+        λ(fn : a → a) →
+        λ(ls : NonEmpty a) →
+          Optional/fold
+            (NonYtpme a)
+            (List/unsnoc a ls.tail)
+            (NonEmpty a)
+            ( λ(x : NonYtpme a) →
+                { head = fn ls.head
+                , tail = List/map a a fn x.init # [ x.last ]
+                }
+            )
+            ls
+
+  let Lines
+      : Type
+      = NonEmpty Text
+
+  let Block
+      : Type
+      = < Simple : Text | Complex : Lines >
+
+  let Block/toLines
+      : Block → Lines
+      = λ(block : Block) →
+          merge
+            { Simple = NonEmpty/singleton Text
+            , Complex = Function/identity Lines
+            }
+            block
+
+  let manyBlocks
+      : ∀(a : Type) → Text → (NonEmpty a → Lines) → List a → Block
+      = λ(a : Type) →
+        λ(ifEmpty : Text) →
+        λ(render : NonEmpty a → Lines) →
+        λ(inputs : List a) →
+          Optional/fold
+            (NonEmpty a)
+            (List/uncons a inputs)
+            Block
+            (λ(inputs : NonEmpty a) → Block.Complex (render inputs))
+            (Block.Simple ifEmpty)
+
+  let blockToText
+      : Block → Text
+      = λ(block : Block) →
+          Text/concatMap
+            Text
+            (λ(line : Text) → line ++ "\n")
+            (NonEmpty/toList Text (Block/toLines block))
+
+  let addPrefix = λ(prefix : Text) → λ(line : Text) → prefix ++ line
+
+  let addIndent = addPrefix "  "
+
+  let indentTail = NonEmpty/mapTail Text addIndent
+
+  let Format =
+          ./Format.dhall
+            sha256:d7936b510cfc091faa994652af0eb5feb889cd44bc989edbe4f1eb8c5623caac
+        ? ./Format.dhall
+
+  let ObjectField = { mapKey : Text, mapValue : Block }
+
+  let -- Essentially the same thing as `Text/show`, except that this does not
+      -- escape `$`
+      escape =
+        List/fold
+          (Text → Text)
+          [ Text/replace "\"" "\\\""
+          , Text/replace "\b" "\\b"
+          , Text/replace "\f" "\\f"
+          , Text/replace "\n" "\\n"
+          , Text/replace "\r" "\\r"
+          , Text/replace "\t" "\\t"
+          , Text/replace "\\" "\\\\"
+          ]
+          Text
+          (λ(replace : Text → Text) → λ(text : Text) → replace text)
+
+  let renderJSONStruct =
+        λ(prefix : Text) →
+        λ(suffix : Text) →
+        λ(blocks : NonEmpty Lines) →
+          let indent = List/map Text Text addIndent
+
+          let appendComma
+              : Lines → Lines
+              = NonEmpty/mapLast Text (λ(line : Text) → line ++ ",")
+
+          let blocks = NonEmpty/mapLeading Lines appendComma blocks
+
+          let block = NonEmpty/concat Text blocks
+
+          in  Optional/fold
+                (NonYtpme Text)
+                (List/unsnoc Text block.tail)
+                (NonEmpty Text)
+                ( λ(ny : NonYtpme Text) →
+                    { head = prefix
+                    , tail =
+                          indent ([ block.head ] # ny.init # [ ny.last ])
+                        # [ suffix ]
+                    }
+                )
+                (NonEmpty/singleton Text "${prefix} ${block.head} ${suffix}")
+
+  let renderObject =
+        λ(format : Format) →
+        λ(fields : NonEmpty ObjectField) →
+          let keystr = λ(field : ObjectField) → "\"${escape field.mapKey}\":"
+
+          let prefixKeyOnFirst =
+                λ(field : ObjectField) →
+                  NonEmpty/mapHead
+                    Text
+                    (addPrefix "${keystr field} ")
+                    (Block/toLines field.mapValue)
+
+          let prependKeyLine =
+                λ(field : ObjectField) →
+                  NonEmpty/prepend
+                    Text
+                    (keystr field)
+                    (Block/toLines field.mapValue)
+
+          let renderYAMLField =
+                λ(field : ObjectField) →
+                  merge
+                    { Simple =
+                        λ(line : Text) →
+                          NonEmpty/singleton Text "${keystr field} ${line}"
+                    , Complex = λ(_ : Lines) → indentTail (prependKeyLine field)
+                    }
+                    field.mapValue
+
+          in  merge
+                { JSON =
+                    renderJSONStruct
+                      "{"
+                      "}"
+                      (NonEmpty/map ObjectField Lines prefixKeyOnFirst fields)
+                , YAML =
+                    NonEmpty/concat
+                      Text
+                      (NonEmpty/map ObjectField Lines renderYAMLField fields)
+                }
+                format
+
+  let renderYAMLArrayField =
+        λ(block : Block) →
+          NonEmpty/mapHead
+            Text
+            (addPrefix "- ")
+            (indentTail (Block/toLines block))
+
+  let renderArray =
+        λ(format : Format) →
+        λ(fields : NonEmpty Block) →
+          merge
+            { JSON =
+                renderJSONStruct
+                  "["
+                  "]"
+                  (NonEmpty/map Block Lines Block/toLines fields)
+            , YAML =
+                NonEmpty/concat
+                  Text
+                  (NonEmpty/map Block Lines renderYAMLArrayField fields)
+            }
+            format
+
+  let renderAs
+      : Format → JSON.Type → Text
+      = λ(format : Format) →
+        λ(json : JSON.Type) →
+          blockToText
+            ( json
+                Block
+                { string = λ(x : Text) → Block.Simple "\"${escape x}\""
+                , double = λ(x : Double) → Block.Simple (Double/show x)
+                , integer = λ(x : Integer) → Block.Simple (JSON.renderInteger x)
+                , object = manyBlocks ObjectField "{}" (renderObject format)
+                , array = manyBlocks Block "[]" (renderArray format)
+                , bool =
+                    λ(x : Bool) → Block.Simple (if x then "true" else "false")
+                , null = Block.Simple "null"
+                }
+            )
+
+  in  renderAs

JSON/renderCompact.dhall

@@ -0,0 +1,52 @@
+--| This renders JSON on a single line
+let JSON = ./core.dhall
+
+let Text/concatMapSep = ../Text/concatMapSep.dhall
+
+let renderInteger = ./renderInteger.dhall
+
+let renderCompact
+    : JSON.Type → Text
+    = λ(j : JSON.Type) →
+        j
+          Text
+          { string = Text/show
+          , double = Double/show
+          , integer = renderInteger
+          , object =
+              λ(x : List { mapKey : Text, mapValue : Text }) →
+                let body =
+                      Text/concatMapSep
+                        ","
+                        { mapKey : Text, mapValue : Text }
+                        ( λ(e : { mapKey : Text, mapValue : Text }) →
+                            " ${Text/show e.mapKey}: ${e.mapValue}"
+                        )
+                        x
+
+                in  "{${body} }"
+          , array =
+              λ(x : List Text) →
+                let body = Text/concatMapSep "," Text (λ(y : Text) → " ${y}") x
+
+                in  "[${body} ]"
+          , bool = λ(x : Bool) → if x then "true" else "false"
+          , null = "null"
+          }
+
+let example =
+        assert
+      :   renderCompact
+            ( JSON.array
+                [ JSON.bool True
+                , JSON.string "Hello"
+                , JSON.object
+                    [ { mapKey = "foo", mapValue = JSON.null }
+                    , { mapKey = "bar", mapValue = JSON.double 1.1 }
+                    , { mapKey = "baz", mapValue = JSON.integer +2 }
+                    ]
+                ]
+            )
+        ≡ "[ true, \"Hello\", { \"foo\": null, \"bar\": 1.1, \"baz\": 2 } ]"
+
+in  renderCompact

JSON/renderInteger.dhall

@@ -0,0 +1,20 @@
+{-|
+Render an `Integer` value as a `JSON number`, according to the JSON standard, in
+which a number may not start with a plus sign (`+`).
+-}
+let Integer/nonNegative = ../Integer/nonNegative.dhall
+
+let renderInteger
+    : Integer → Text
+    = λ(integer : Integer) →
+        if    Integer/nonNegative integer
+        then  Natural/show (Integer/clamp integer)
+        else  Integer/show integer
+
+let positive = assert : renderInteger +1 ≡ "1"
+
+let zero = assert : renderInteger +0 ≡ "0"
+
+let negative = assert : renderInteger -1 ≡ "-1"
+
+in  renderInteger

JSON/renderYAML.dhall

@@ -0,0 +1,12 @@
+λ(nix : ../NixPrelude.dhall) →
+  let JSON = ./core.dhall
+
+  let Format = ./Format.dhall
+
+  let renderAs = ./renderAs.dhall nix
+
+  let renderYAML
+      : JSON.Type → Text
+      = renderAs Format.YAML
+
+  in  renderYAML

JSON/string.dhall

@@ -0,0 +1,32 @@
+{-|
+Create a JSON string from Dhall `Text`
+
+```
+let JSON = ./package.dhall
+in  JSON.render (JSON.string "ABC $ \" 🙂")
+= "\"ABC \\u0024 \\\" 🙂\""
+
+let JSON = ./package.dhall
+in  JSON.render (JSON.string "")
+= "\"\""
+```
+-}
+let JSON = ./Type.dhall
+
+let string
+    : Text → JSON
+    = λ(x : Text) →
+      λ(JSON : Type) →
+      λ ( json
+        : { array : List JSON → JSON
+          , bool : Bool → JSON
+          , double : Double → JSON
+          , integer : Integer → JSON
+          , null : JSON
+          , object : List { mapKey : Text, mapValue : JSON } → JSON
+          , string : Text → JSON
+          }
+        ) →
+        json.string x
+
+in  string

JSON/tagInline.dhall

@@ -0,0 +1,23 @@
+--| Prepare a union value for JSON- or YAML-encoding with the inline layout
+let Nesting = ./Nesting.dhall
+
+let Tagged = ./Tagged.dhall
+
+let tagInline
+    : Text → ∀(a : Type) → a → Tagged a
+    = λ(tagFieldName : Text) →
+      λ(a : Type) →
+      λ(contents : a) →
+        { nesting = Nesting.Inline, field = tagFieldName, contents }
+
+let example0 =
+      let Example = < Left : { foo : Natural } | Right : { bar : Bool } >
+
+      in    assert
+          :   tagInline "name" Example (Example.Left { foo = 2 })
+            ≡ { field = "name"
+              , nesting = Nesting.Inline
+              , contents = Example.Left { foo = 2 }
+              }
+
+in  tagInline

JSON/tagNested.dhall

@@ -0,0 +1,27 @@
+--| Prepare a union value for JSON- or YAML-encoding with the nested layout
+let Nesting = ./Nesting.dhall
+
+let Tagged = ./Tagged.dhall
+
+let tagNested
+    : Text → Text → ∀(a : Type) → a → Tagged a
+    = λ(contentsFieldName : Text) →
+      λ(tagFieldName : Text) →
+      λ(a : Type) →
+      λ(contents : a) →
+        { nesting = Nesting.Nested contentsFieldName
+        , field = tagFieldName
+        , contents
+        }
+
+let example0 =
+      let Example = < Left : { foo : Natural } | Right : { bar : Bool } >
+
+      in    assert
+          :   tagNested "value" "name" Example (Example.Left { foo = 2 })
+            ≡ { field = "name"
+              , nesting = Nesting.Nested "value"
+              , contents = Example.Left { foo = 2 }
+              }
+
+in  tagNested

Text/default.dhall

@@ -1,10 +1,9 @@
 --| Unwrap an `Optional` `Text` value, defaulting `None` to `""`
-let default
-    : Optional Text → Text
-    = λ(o : Optional Text) → merge { Some = λ(t : Text) → t, None = "" } o
+λ(nix : ../NixPrelude.dhall) →
+  let Optional/default = ../Optional/default.dhall nix
 
-let example0 = assert : default (Some "ABC") ≡ "ABC"
+  let default
+      : Optional Text → Text
+      = λ(o : Optional Text) → Optional/default Text "" o
 
-let example1 = assert : default (None Text) ≡ ""
-
-in  default
+  in  default

Text/defaultMap.dhall

@@ -1,13 +1,14 @@
 --| Transform the value in an `Optional` into `Text`, defaulting `None` to `""`
-let defaultMap
-    : ∀(a : Type) → (a → Text) → Optional a → Text
-    = λ(a : Type) →
-      λ(f : a → Text) →
-      λ(o : Optional a) →
-        merge { Some = f, None = "" } o
+λ(nix : ../NixPrelude.dhall) →
+  let Optional/map = ../Optional/map.dhall nix
 
-let example0 = assert : defaultMap Natural Natural/show (Some 0) ≡ "0"
+  let default = ./default.dhall nix
 
-let example1 = assert : defaultMap Natural Natural/show (None Natural) ≡ ""
+  let defaultMap
+      : ∀(a : Type) → (a → Text) → Optional a → Text
+      = λ(a : Type) →
+        λ(f : a → Text) →
+        λ(o : Optional a) →
+          default (Optional/map a Text f o)
 
-in  defaultMap
+  in  defaultMap

Text/package.dhall

@@ -1,14 +1,15 @@
-{ concat = ./concat.dhall
-, concatMap = ./concatMap.dhall
-, concatMapSep = ./concatMapSep.dhall
-, concatSep = ./concatSep.dhall
-, default = ./default.dhall
-, defaultMap = ./defaultMap.dhall
-, lowerASCII = ./lowerASCII.dhall
-, replace = ./replace.dhall
-, replicate = ./replicate.dhall
-, shell-escape = ./shell-escape.dhall
-, show = ./show.dhall
-, spaces = ./spaces.dhall
-, upperASCII = ./upperASCII.dhall
-}
+λ(nix : ../NixPrelude.dhall) →
+  { concat = ./concat.dhall
+  , concatMap = ./concatMap.dhall
+  , concatMapSep = ./concatMapSep.dhall
+  , concatSep = ./concatSep.dhall
+  , default = ./default.dhall nix
+  , defaultMap = ./defaultMap.dhall nix
+  , lowerASCII = ./lowerASCII.dhall
+  , replace = ./replace.dhall
+  , replicate = ./replicate.dhall
+  , shell-escape = ./shell-escape.dhall
+  , show = ./show.dhall
+  , spaces = ./spaces.dhall
+  , upperASCII = ./upperASCII.dhall
+  }

package.dhall

@@ -4,6 +4,7 @@
   , Double = ./Double/package.dhall nix
   , Function = ./Function/package.dhall
   , Integer = ./Integer/package.dhall nix
+  , JSON = ./JSON/package.dhall nix
   , List = ./List/package.dhall nix
   , Location = ./Location/package.dhall
   , Map = ./Map/package.dhall nix
@@ -15,5 +16,5 @@
   , Optional = ./Optional/package.dhall nix
   , Path = ./Path/package.dhall nix
   , Set = ./Set/package.dhall nix
-  , Text = ./Text/package.dhall
+  , Text = ./Text/package.dhall nix
   }