example: add fun dotenv example

Cargo.toml

@@ -35,3 +35,7 @@ maintenance = { status = "actively-developed" }
 [[example]]
 name = "calc"
 required-features = ["vec", "number"]
+
+[[example]]
+name = "dotenv"
+required-features = ["vec", "tuple"]

examples/dotenv.rs

@@ -0,0 +1,25 @@
+use estring::{EString, Pair, SepVec};
+
+const DOTENV_CONTENT: &str = "\
+DATABASE_URL=postgres://user:password@localhost:5432/recipes
+APP_HOST=http://localhost:3000";
+
+fn main() -> Result<(), estring::ParseError> {
+    EString::from(DOTENV_CONTENT)
+        .parse::<SepVec<Pair<&str, '=', &str>, '\n'>>()?
+        .iter()
+        .for_each(|p @ Pair(key, value)| {
+            println!("pair: {}", p);
+
+            std::env::set_var(key, value);
+        });
+
+    println!(
+        "envs: {:#?}",
+        std::env::vars()
+            .filter(|(k, ..)| ["DATABASE_URL", "APP_HOST"].contains(&k.as_str()))
+            .collect::<Vec<_>>()
+    );
+
+    Ok(())
+}