Go back to using --omitNull instead of --omitEmpty (#110)

Fixes #86

The motivation of this is to more accurately model the Kubernetes
API semantics by not auto-omitting empty fields.  This is because
a field set to `Some ([] : List T)` is not necessarily the same
as `None (List T)`.

This makes the typical case a bit more verbose (more `Some`s), but
the difference to the `./examples` shows that it's not too bad.

1.12/README.md

@@ -53,12 +53,15 @@ In the following example, we:
 -- examples/deploymentSimple.dhall
 
 let kubernetes =
-      ../package.dhall sha256:ce1e73deebf8c4eb513bfc736adfd924fe696ffee486f6f4bd81ed281bbf0f2a
+      ../package.dhall sha256:d545c49903546ab1b4186886c78afec2c406200c42be38a33b15fd1c71acaa9d
 
 let deployment =
       kubernetes.Deployment::{
       , metadata = kubernetes.ObjectMeta::{ name = "nginx" }
       , spec = Some kubernetes.DeploymentSpec::{
+        , selector = kubernetes.LabelSelector::{
+          , matchLabels = Some (toMap { name = "nginx" })
+          }
         , replicas = Some 2
         , template = kubernetes.PodTemplateSpec::{
           , metadata = kubernetes.ObjectMeta::{ name = "nginx" }
@@ -67,7 +70,8 @@ let deployment =
               [ kubernetes.Container::{
                 , name = "nginx"
                 , image = Some "nginx:1.15.3"
-                , ports = [ kubernetes.ContainerPort::{ containerPort = 80 } ]
+                , ports = Some
+                    [ kubernetes.ContainerPort::{ containerPort = 80 } ]
                 }
               ]
             }
@@ -82,7 +86,7 @@ in  deployment
 We then run this through `dhall-to-yaml` to generate our Kubernetes definition:
 
 ```bash
-dhall-to-yaml --omit-empty < examples/deploymentSimple.dhall
+dhall-to-yaml < examples/deploymentSimple.dhall
 ```
 
 And we get:
@@ -95,6 +99,9 @@ metadata:
   name: nginx
 spec:
   replicas: 2
+  selector:
+    matchLabels:
+      name: nginx
   template:
     metadata:
       name: nginx
@@ -130,7 +137,7 @@ Things to note in the following example:
   them over the list of services.
 - we also defined the list of `services` inline, but you should instead return the
   `mkIngress` function instead of applying it, so you can do something like
-  `dhall-to-yaml --omit-empty <<< "./mkIngress.dhall ./myServices.dhall"`
+  `dhall-to-yaml <<< "./mkIngress.dhall ./myServices.dhall"`
 
 ```dhall
 -- examples/ingress.dhall
@@ -140,10 +147,8 @@ let Prelude =
 
 let map = Prelude.List.map
 
-let kv = Prelude.JSON.keyText
-
 let kubernetes =
-      ../package.dhall sha256:ce1e73deebf8c4eb513bfc736adfd924fe696ffee486f6f4bd81ed281bbf0f2a
+      ../package.dhall sha256:d545c49903546ab1b4186886c78afec2c406200c42be38a33b15fd1c71acaa9d
 
 let Service = { name : Text, host : Text, version : Text }
 
@@ -152,7 +157,7 @@ let services = [ { name = "foo", host = "foo.example.com", version = "2.3" } ]
 let makeTLS
     : Service → kubernetes.IngressTLS.Type
     =   λ(service : Service)
-      → { hosts = [ service.host ]
+      → { hosts = Some [ service.host ]
         , secretName = Some "${service.name}-certificate"
         }
 
@@ -176,9 +181,10 @@ let mkIngress
     : List Service → kubernetes.Ingress.Type
     =   λ(inputServices : List Service)
       → let annotations =
-              [ kv "kubernetes.io/ingress.class" "nginx"
-              , kv "kubernetes.io/ingress.allow-http" "false"
-              ]
+              toMap
+                { `kubernetes.io/ingress.class` = "nginx"
+                , `kubernetes.io/ingress.allow-http` = "false"
+                }
 
         let defaultService =
               { name = "default"
@@ -190,20 +196,26 @@ let mkIngress
 
         let spec =
               kubernetes.IngressSpec::{
-              , tls =
-                  map Service kubernetes.IngressTLS.Type makeTLS ingressServices
-              , rules =
-                  map
-                    Service
-                    kubernetes.IngressRule.Type
-                    makeRule
-                    ingressServices
+              , tls = Some
+                  ( map
+                      Service
+                      kubernetes.IngressTLS.Type
+                      makeTLS
+                      ingressServices
+                  )
+              , rules = Some
+                  ( map
+                      Service
+                      kubernetes.IngressRule.Type
+                      makeRule
+                      ingressServices
+                  )
               }
 
         in  kubernetes.Ingress::{
             , metadata = kubernetes.ObjectMeta::{
               , name = "nginx"
-              , annotations = annotations
+              , annotations = Some annotations
               }
             , spec = Some spec
             }
@@ -215,7 +227,7 @@ in  mkIngress services
 As before we get the yaml out by running:
 
 ```bash
-dhall-to-yaml --omit-empty < examples/ingress.dhall
+dhall-to-yaml < examples/ingress.dhall
 ```
 
 Result:
@@ -264,7 +276,7 @@ If the objects have the same type, this is very easy: you return a Dhall list co
 objects, and use the `--documents` flag, e.g.:
 
 ```bash
-dhall-to-yaml --documents --omit-empty <<< "let a = ./examples/deploymentSimple.dhall in [a, a]"
+dhall-to-yaml --documents <<< "let a = ./examples/deploymentSimple.dhall in [a, a]"
 ```
 
 If the objects are of different type, it's not possible to have separate documents in the same YAML file.