[Examples] Add examples of how to map over generic and labelled repre…

…sentations (#192)

* [Examples] Add examples of how to map over generic and labelled representations

```
❯ cargo run --example generic
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/examples/generic`
Joe
First name: bo
Last name: peep
age: 30
❯ cargo run --example labelled
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/examples/labelled`
Blow
ExternalPerson {
    age: 10,
    address: ExternalAddress {
        name: "somewhere out there",
        phone: ExternalPhoneNumber {
            main: 1234,
        },
    },
    name: "John",
}
first_name: bo
last_name: peep
age: 30
```

.github/workflows/ci.yml

@@ -100,17 +100,11 @@ jobs:
         with:
           command: build
       - uses: actions-rs/cargo@v1
-        name: std build generic example
+        name: std build examples
         if: ${{ matrix.use_std == 'n' }}
         with:
           command: build
-          args: --example generic
-      - uses: actions-rs/cargo@v1
-        name: std build labelled example
-        if: ${{ matrix.use_std == 'n' }}
-        with:
-          command: build
-          args: --example labelled
+          args: --examples
 
   test:
     name: Test Suite

examples/generic.rs

@@ -40,4 +40,18 @@ fn main() {
         ..p
     });
     assert_eq!(oldest_person.age, 90);
+
+    // mapping over generic representation
+    let peep = Person {
+        first_name: "bo",
+        last_name: "peep",
+        age: 30,
+    };
+    let generic = frunk::into_generic(peep);
+    // mapping each one
+    let _ = generic.map(hlist![
+        |first_name| println!("First name: {}", first_name),
+        |last_name| println!("Last name: {}", last_name),
+        |age| println!("age: {}", age),
+    ]);
 }

examples/labelled.rs

@@ -100,4 +100,18 @@ fn main() {
 
     let external_person: ExternalPerson = internal_person.transmogrify();
     println!("{:#?}", external_person);
+
+    // mapping over labelled generic representation
+    let peep = NewUser {
+        first_name: "bo",
+        last_name: "peep",
+        age: 30,
+    };
+    let labelled_generic = frunk::into_labelled_generic(peep);
+
+    let _ = labelled_generic.map(hlist![
+        |f: Field<_, _>| println!("{}: {}", f.name, f.value),
+        |l: Field<_, _>| println!("{}: {}", l.name, l.value),
+        |a: Field<_, _>| println!("{}: {}", a.name, a.value),
+    ]);
 }