This project needs capnproto and should mention it

[svenstaro]

When naively trying to build an example project, one gets this:

thread '<main>' panicked at 'called `Result::unwrap()` on an `Err` value: Error { kind: Failed, description: "Error while trying to execute `capnp compile`: Failed: No such file or directory (os error 2).  Please verify that version 0.5.2 or higher of the capnp executable is installed on your system. See https://capnproto.org/install.html" }', src/libcore/result.rs:746
note: Run with `RUST_BACKTRACE=1` for a backtrace.

You should mention that you require capnproto to be installed in the system beforehand.

[ehiggs]

My understanding is that there should be a capnp-sys crate which builds capnproto and provides a thin ffi wrapper around it. The capnp crate should then add a 'rustic' API. This is the intended cargo use case since it means crates can be built with minimal requirements from the environment. iow, OS installed libraries are for the OS and system administration tools. Build system libraries are for applications so they can manage the dependencies with fine control.

[svenstaro]

That would work.