conditional optional unwrapping

TODO.md

@@ -80,7 +80,7 @@
     - function-like macros and non-literal macro expressions remain unsupported
   - static inline functions (implemented)
 
-- 5. control flow
+5. control flow
   - boolean expressions (implemented)
     - `bool` type with `true` / `false` literals
     - comparison operators: `==`, `!=`, `<`, `<=`, `>`, `>=` (numeric operands widen; `bool` supports only `==` / `!=`)
@@ -89,7 +89,10 @@
   - if statements (implemented). example: `if condition { ... } else if { ... } else { ... }`
     - conditions must be `bool`; block-scoped locals with shadowing across blocks
     - lowered through new `Label` / `Br` / `Cond_Br` IR opcodes (alloca-backed locals, no phi nodes)
-  - conditional unwrapping for optionals (`?T`): `if val |v| { ... } else { ... }` - unwrap `val` into `v` if it is not `none`
+  - conditional unwrapping for optionals (`?T`) (implemented): `if val |v| { ... } else { ... }` - unwrap `val` into `v` if it is not `none`
+    - single immutable binding scoped to the then-block; `v` not visible in `else` or after the `if`
+    - `|` lexes as a new `Pipe` token; the `.If` reuses AST `name` / HIR `local` to carry the binding (no new statement kind)
+    - new `Optional_Is_Some` / `Optional_Value` IR opcodes (the `Unwrap` presence-test + extract, minus the trap)
   - conditional unwrapping with guard clause:  `if val |v : v >= 10| { ... } else { ... }` - unwrap `val` into `v` if it is not `none`
   - multi-unwrap (see section below)
   - while loops (operates on boolean conditions). examples:
@@ -106,6 +109,9 @@
     - `for 0..(len) |i| { ... }` or equivalently `for 0..=(len - 1) |i| { ... }` - calculating range bounds, expressions must be parenthesized
   - for all conditionals/guards, parentheses are optional but allowed for visual clarity
 
+6. compound assignment
+
+
 ## A word on multi-unwrap
 
 Unwrap multiple optionals with `and`. This **short-circuits**: if the first optional is none, subsequent expressions are not evaluated.