Merge pull request #109 from NLnetLabs/changelog-update

Update changelog for 0.4.0

Changelog.md

@@ -1,15 +1,53 @@
 # Changelog
 
-## Unreleased new version
+## 0.4.0
 
-Release yyyy-mm-dd.
+Release 2025-01-29.
 
 ### Breaking changes
 
+- Filter maps no longer have a `define` and an `apply` block. `let` bindings
+  should be used instead. For example:
+
+```roto
+# Roto 0.3
+filter-map foo() {
+    define {
+        x = 4;
+    }
+    apply {
+        accept x;
+    }
+}
+
+# Roto 0.4
+filter-map foo() {
+    let x = 4;
+    accept x;
+}
+```
+
 ### New
 
+- Variables can now be created in more places with `let` bindings. `let`
+  bindings replace the `define`/`apply` mechanism and are much more general
+  because they can be used in any block. For example, inside functions or
+  `if`-`else` blocks. The binding is scoped until the end of the block it is
+  defined in. It is not allowed to declare multiple variables with the same
+  name within a single block.
+- The `String` type was added to represent pieces of text. String literals
+  are enclosed in double quotes (`"`).
+- It is now possible to declare constants in the runtime for a Roto script.
+- Similarly, it is now possible to add "context" to Roto scripts. The variables
+  in the context behave like constants, but they can differ between different
+  calls to a script. In other words, constants are defined when the script is
+  _compiled_, context is defined when the script is _run_.
+
 ### Bug fixes
 
+- 64-bit numbers (i.e. `i64` and `u64`) were not type checked and compiled
+  properly. They are now fixed.
+
 ## 0.3.0
 
 Released 2024-11-21.