[augustohp]

I like the "slim" approach on LOC, kudos to that. I would point some - IMO - design problems:

# Static attributes and methods. Are they really needed? They are difficult to test and predict, specially the public attributes.

# The "echo"s on routes. Since every route is a method (encapsulated by one), this behavior could be easily avoided (easier to test and control). You are already using callables, you can easily test (and run) matching routes to execute any callable until a stream is given (on Respect/Rest we learned what a powerful feature it is).

# Lack of tests. Although low LOC, there is much happening, specially on the "dispatch" method (it would be awesome to know through tests what the If's/Else's actually do and prevent).

# Why (as mentioned before) the error header do not provide a proper HTTP header!? It would also be nice to provide two different error routes: one for client errors (404: not found, forbidden) and another to server errors (HTTP/1.1 500 Server Error).

A suggestion (we've been talking a lot on Respect/Rest) is to implement the URI Template (RFC 6570) for matching routes and hydration of parameters (something macaw lacks but i like using the PHP way of $_GET, $_POST and filter_input()). With a component dealing nicely with URI Templates many projects would benefit from it.