added variables

SPEC.md

@@ -25,6 +25,7 @@
   - `lookup`: resolves token → word entry; can be replaced to build new namespaces or module systems.
 - **Definition form**: `word <name> ... end` is the required way to declare high-level words. Legacy `: <name> ... ;` definitions are no longer accepted.
 - **Text macros**: `macro <name> [param_count] ... ;` records tokens until the closing `;` and registers a macro that performs positional substitution (`$1`, `$2`, ...). The old `macro: ... ;macro` form is removed.
+- **Lexical stack aliases**: `with a b in ... end` rewrites the body so `a`/`b` expand to stable `rpick` accesses. Values are moved to the return stack on entry and released with `rdrop` on exit, giving cheap locally named slots while keeping the data stack free for intermediate results.
 - **Compile vs interpret**: Each word advertises stack effect + immediacy. Immediate words execute during compilation (macro behavior). Others emit code or inline asm.
 - **Syntax morphing**: Provide primitives `set-reader`, `with-reader`, and word-lists so layers (e.g., Lisp-like forms) can be composed.
 - **Inline Python hooks**: `:py name { ... } ;` executes the enclosed Python block immediately, then registers `name` as a word whose behavior is provided by that block. Define a `macro(ctx)` function to intercept compilation (receiving a `MacroContext` with helpers like `next_token`, `emit_literal`, `new_label`, `inject_tokens`, and direct access to the active parser), and/or an `intrinsic(builder)` function to emit custom assembly. This lets end users extend the language—parsing source, manipulating AST nodes, or writing NASM—without touching the bootstrap source. The standard library’s `extend-syntax` and `fn` forms are ordinary `:py` blocks built with these APIs, so users can clone or replace them entirely from L2 source files.