CHANGELOG!

CHANGELOG.md

@@ -39,13 +39,61 @@
   aren't located at the root of their repository:
 
   ```toml
-  repository = { type = "github", user = "gleam-lang", repo = "gleam", path = "packages/my_package" }
+  repository = {
+    type = "github",
+    user = "gleam-lang",
+    repo = "gleam",
+    path = "packages/my_package"
+  }
   ```
 
   ([Richard Viney](https://github.com/richard-viney))
 
+- The build tool now refuses to publish any incomplete package that has any
+  `echo` debug printing left.
+  ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
+
 ### Compiler
 
+- You can now use the `echo` keyword to debug print any value: `echo` can be
+  followed by any expression and it will print it to stderr alongside the module
+  it comes from and its line number. This:
+
+  ```gleam
+  pub fn main() {
+    echo [1, 2, 3]
+  }
+  ```
+
+  Will output to stderr:
+
+  ```txt
+  /src/module.gleam:2
+  [1, 2, 3]
+  ```
+
+  `echo` can also be used in the middle of a pipeline. This:
+
+  ```gleam
+  pub fn main() {
+    [1, 2, 3]
+    |> echo
+    |> list.map(fn(x) { x * 2 })
+    |> echo
+  }
+  ```
+
+  Will output to stderr:
+
+  ```txt
+  /src/module.gleam:3
+  [1, 2, 3]
+  /src/module.gleam:5
+  [2, 4, 6]
+  ```
+
+  ([Giacomo Cavalieri](https://github.com/giacomocavalieri))
+
 - The compiler now prints correctly qualified or aliased type names when
   printing type errors.