Adding README

README

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+# zlox, a clox rewrite in Zig.
+
+While reading [Crafting Interpreters](https://craftinginterpreters.com/), after having rewrote the interpreter part in Rust (see [rs-lox](https://github.com/mycroft/rs-lox)), I'm now attempting to write the bytecode compiler in Zig.
+
+## Progression
+
+- [x] 14 - Chunks of Bytecode
+- [x] 15 - A Virtual Machine
+- [x] 16 - Scanning on Demand
+- [x] 17 - Compiling Expressions
+- [ ] 18 - Types of Values
+- [ ] 19 - Strings
+- [ ] 20 - Hash Tables
+- [ ] 21 - Global Variables
+- [ ] 22 - Local Variables
+- [ ] 23 - Jumping Back and Forth
+- [ ] 24 - Calls and Functions
+- [ ] 25 - Closures
+- [ ] 26 - Garbage Collection
+- [ ] 27 - Classes and Instances
+- [ ] 28 - Method and Initializers
+- [ ] 29 - Superclasses
+- [ ] 30 - Optimization
+
+## Build & run
+
+There is a `justfile` to help building & running:
+
+```sh
+$ just build
+$ ls -l zig-out/bin/zlox
+-rwxr-xr-x 1 mycroft mycroft 2823296 Aug 25 15:36 zig-out/bin/zlox
+
+$ just run
+zig build run
+> 2*3 + 3*4
+== code ==
+0000    1      OP_CONSTANT    0 '2'
+0002    |      OP_CONSTANT    1 '3'
+0004    |      OP_MULTIPLY
+0005    |      OP_CONSTANT    2 '3'
+0007    |      OP_CONSTANT    3 '4'
+0009    |      OP_MULTIPLY
+000a    |           OP_ADD
+== end of code ==
+
+0000    1      OP_CONSTANT    0 '2'
+                                [ 2 ]
+0002    |      OP_CONSTANT    1 '3'
+                                [ 2 ][ 3 ]
+0004    |      OP_MULTIPLY
+                                [ 6 ]
+0005    |      OP_CONSTANT    2 '3'
+                                [ 6 ][ 3 ]
+0007    |      OP_CONSTANT    3 '4'
+                                [ 6 ][ 3 ][ 4 ]
+0009    |      OP_MULTIPLY
+                                [ 6 ][ 12 ]
+000a    |           OP_ADD
+                                [ 18 ]
+000b    2        OP_RETURN
+18
+>
+
+```