app

examples/app/

Sample Echo programs that exercise the language surface and a small HTTP app.

File	Role
surface.echo	Kitchen sink — full surface + user / user_extra
main.echo	Finite HTTP demo: in-process dispatch + live TCP smoke
server.echo	Long-running HTTP server (http.serve)
config.echo	# constants + export
user.echo	% user shape + methods
user_extra.echo	@ user extra members
users.echo	free helpers + user.user { … } lits
routes.echo	handlers as function values

cargo build -p xo
./target/debug/xo run --no-cache examples/app/surface.echo
./target/debug/xo run --no-cache examples/app/main.echo
./target/debug/xo run --no-cache examples/app/server.echo   # blocks; curl /health
./target/debug/xo check examples/app/main.echo

Imports are module-scoped: / std/io → io.log, not bare log. See docs/modules.md.

What main.echo does

1. Builds routes and dispatches sample GETs in-process (no sockets).
2. Listens on 127.0.0.1:18080, serves one real connection via http.handle_connection in a task (+ () [lis, table] { … }), client GET /health, then joins and exits (finite; e26/CI friendly).

What server.echo does

Calls http.serve("0.0.0.0:8080", routes) — nonblocking accept loop, one task per connection (+ handle_connection(conn, routes)).

# terminal 1
./target/debug/xo run --no-cache examples/app/server.echo

# terminal 2
curl -s http://127.0.0.1:8080/
curl -s http://127.0.0.1:8080/health
curl -s http://127.0.0.1:8080/users

Surface coverage (surface.echo)

Area	Exercised
Leaders ~ $ # % @	binds, shape, @ extra members
Leaders ? :	if / else-if / else
Leaders * < >	loops
Leaders |	match
Leaders ! ^	result / return
Leaders / \	import / export
Leaders + -	tasks (also in main.echo live smoke)
Free fns / methods	counters, user
Lits / collections / ops	kitchen sink

When you lock a new language feature, extend surface.echo (or a sibling) and keep xo run green for surface.echo and main.echo.