Base64 (en|de)coding (#7)

fixes #4

README.md

@@ -3,6 +3,25 @@
 [![Package Version](https://img.shields.io/hexpm/v/lustre_hash_state)](https://hex.pm/packages/lustre_hash_state)
 [![Hex Docs](https://img.shields.io/badge/hex-docs-ffaff3)](https://hexdocs.pm/lustre_hash_state/)
 
+---
+
+`lustre_hash_state` provides `Effect`s to store a model's state in the
+hash fragment:
+
+```
+type Model {
+  Model(dict.from_list([#("example_key", "example_value")]))
+}
+```
+
+```txt
+https://example.com/#example_key=example_value
+```
+
+When the model changes, the hash changes! When the hash changes, the model changes, too!
+
+## Usage
+
 ```sh
 gleam add lustre_hash_state
 ```
@@ -12,32 +31,30 @@ import lustre_hash_state
 
 pub opaque type Msg {
   // ...
+  // Bring your own key value Msg type
   HashChange(key: String, value: String)
 }
 
-pub fn main() {
-  let app = lustre.application(init, update, view)
-  let assert Ok(_) = lustre.start(app, "#app", Nil)
-}
-
 fn init(_flags) -> #(Model, effect.Effect(Msg)) {
+  // dispatch a HashChange Msg when the "hashchange" event is
+  // dispatched from the browser
   #(Model(dict.new()), lustre_hash_state.init(HashChange))
 }
 
 fn update(model: Model, msg: Msg) -> #(Model, effect.Effect(msg)) {
+  let Model(dct) = model
   case msg {
-    // hash change events can update the model
+    // update the model on hashchange events
     HashChange(key, value) -> {
       #(Model(dict.update(dct, key, fn(_x) { value })), effect.none())
     }
     UserUpdatedMessage(key, value) -> {
       #(
         Model(dict.update(dct, key, fn(_x) { value })),
-        // and user events can update the hash
+        // update the hash with the new key value pair
         lustre_hash_state.update(key, value),
       )
     }
-    // ...
   }
 }
 
@@ -58,6 +75,35 @@ fn view(model: Model) -> Element(Msg) {
 }
 ```
 
+## Encoding
+
+Need to work with data types more complex than strings? No problem!
+
+Within lustre's init fn, decode the data:
+
+```gleam
+fn init(_flags) -> #(Model, effect.Effect(Msg)) {
+  #(
+    Model(dict.new()),
+    lustre_hash_state.init(fn(key: String, value: String) {
+      // decoded using the `from_base64` convenience method
+      HashChange(key, value |> lustre_hash_state.from_base64)
+    }),
+  )
+}
+```
+
+Within lustre's update fn, encode the data:
+
+```gleam
+UserUpdatedMessage(key, value) -> {
+  #(
+    Model(...),
+    lustre_hash_state.update(key, value |> lustre_hash_state.to_base64),
+  )
+}
+```
+
 Further documentation can be found at <https://hexdocs.pm/lustre_hash_state>.
 
 ## Development