A collection of various experiment in using and abusing the Cairo language. I've created the contracts while learning and experimenting with Cairo myself. Most contracts are fully tested. Most work with Cairo v0.6.2, but some require v0.8.0.
The code in calls.cairo and accompanying target.cairo contracts serves to experiment with cross contract invocation (only on Starknet itself, no L1 <-> L2). It employs both the call_contract syscall and invoking another contract via an interface, both in a direct fashion and via delegate calls.
dicts.cairo has, as the name suggests, functions to do with Cairo's dict module.
This contract (echo.cairo) serves to test what happens when you create an infinite invocation loop. Spoiler alert: the transaction fails.
enums.cairo list different patterns on how to declare an enum in cairo.
debug_hints.cairo shows a super useful way how to use hints for debug purposes. In the test suite, a contract is compiled with disable_hint_validation=True which means all hints are fair game. This way, we can add print statements at will to ease debugging. All credit goes to Marcello for discovering this technique.
The visibility dir hold a simple PoC of unintentional functionality creep. On the surface, themain.cairo contract only exposes a single view function. However, because it imports from library.cairo, when deployed, these will be compiled and "merged" together. The deployed contract will also expose increment and get_value as functions. Furthermore, even though increment is marked as a view function, it alters a storage variable 🙈
The state.cairo contract contains various examples on how to store and model data in Cairo. Warning, not all might be sane 😅
Random experiments and peculiarities that don't have a place are in various.cairo.
The using_invoke.cairo shows how to call a function via a pointer, using invoke. It's tricky because it requires non-standard way how to set up implicit arguments via the ap pointer.