diff --git a/TODO.md b/TODO.md
index d631e1c..9295551 100644
--- a/TODO.md
+++ b/TODO.md
@@ -7,5 +7,6 @@
 - [x] Explain about design.
 - [ ] Add more tests
 - [x] Add minimal binding example
+- [ ] Make REPL nicer and add screenshot in README when it looks good.
 - [ ] Add basic capabilities for order sending / receiving.
 - [ ] Make PR to explain idea behind the crate.
diff --git a/doc/DEV_NOTES.md b/doc/DEV_NOTES.md
index 33c56b7..7b1375f 100644
--- a/doc/DEV_NOTES.md
+++ b/doc/DEV_NOTES.md
@@ -41,6 +41,11 @@ quickfix (lang: rust)
 
 ```
 
+About C++ to C binding library:
+
+- `.cpp` file is made of multiple macros to try making it as short as possible.
+- `.h` contains less possible macro to make it easier to compare with rust code.
+
 ## Other project inspiration
 
 - [rust-rdkafka](https://github.com/fede1024/rust-rdkafka): for how to build C library using cmake and link to rust project.