add minimal example and ci

.github/workflows/ci.yaml

@@ -0,0 +1,25 @@
+name: Cargo Build & Test
+
+on:
+  push:
+  pull_request:
+
+env: 
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build_and_test:
+    name: valibuk - latest
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toolchain:
+          - stable
+          - beta
+          - nightly
+    steps:
+      - uses: actions/checkout@v3
+      - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
+      - run: cargo build --verbose
+      - run: cargo test --verbose
+

README.md

@@ -20,6 +20,7 @@ fn is_positive(i: i32) -> Result<i32, String> {
 #[derive(Validated)]
 // 2. And a struct 
 struct A {
+  #[validator(is_positive)] // Apply the function from (1) as validator
   a: i32,
 }
 let i: i32 = 1;
@@ -28,6 +29,8 @@ let a = A::try_from(UnvalidatedA { a: i }).expect("valid instance");
 assert_eq!(a.a, i);
 ```
 
+See more examples in `tests` and `examples`
+
 ## TODO
 
 - [x] Move validator registrations into macro annotations

examples/minimal.rs

@@ -0,0 +1,25 @@
+use valibuk::Validated;
+
+// 1. Having a T -> Result<T, E> validator
+fn is_positive(i: i32) -> Result<i32, String> {
+    if i > 0 {
+        Ok(i)
+    } else {
+        Err("wrong".to_string())
+    }
+}
+
+// 3. Derive (1) the `unvalidated` type and a `std::convert::TryFrom` trait
+#[derive(Validated)]
+// 2. And a struct
+struct A {
+    #[validator(is_positive)] // Apply the function from (1) as validator
+    a: i32,
+}
+
+fn main() {
+    let i: i32 = 1;
+    // 4. Construct the instance of the original type from the unvalidated version
+    let a = A::try_from(UnvalidatedA { a: i }).expect("valid instance");
+    assert_eq!(a.a, i);
+}