Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
52b1b342ab
This PR implements zero cost `BaseIO` by erasing the `IO.RealWorld` parameter from argument lists and structures. This is a **major breaking change for FFI**. Concretely: - `BaseIO` is defined in terms of `ST IO.RealWorld` - `EIO` (and thus `IO`) is defined in terms of `EST IO.RealWorld` - The opaque `Void` type is introduced and the trivial structure optimization updated to account for it. Furthermore, arguments of type `Void s` are removed from the argument lists of the C functions. - `ST` is redefined as `Void s -> ST.Out s a` where `ST.Out` is a pair of `Void s` and `a` This together has the following major effects on our generated code: - Functions that return `BaseIO`/`ST`/`EIO`/`IO`/`EST` now do not take the dummy world parameter anymore. To account for this FFI code needs to delete the dummy world parameter from the argument lists. - Functions that return `BaseIO`/`ST` now return their wrapped value directly. In particular `BaseIO UInt32` now returns a `uint32_t` instead of a `lean_object*`. To account for this FFI code might have to change the return type and does not need to call `lean_io_result_mk_ok` anymore but can instead just `return` values right away (same with extracting values from `BaseIO` computations. - Functions that return `EIO`/`IO`/`EST` now only return the equivalent of an `Except` node which reduces the allocation size. The `lean_io_result_mk_ok`/`lean_io_result_mk_error` functions were updated to account for this already so no change is required. Besides improving performance by dropping allocation (sizes) we can now also do fun new things such as: ```lean @[extern "malloc"] opaque malloc (size : USize) : BaseIO USize ``` |
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