usocket:socket-connect

(usocket:socket-connect host port &key protocol element-type timeout deadline nodelay local-host local-port)

Opens a blocking TCP connection to host and port and returns a socket -- the usocket-compatible entry point over rontolisp:tcp-connect. In this shim a socket IS its stream handle, so usocket:socket-stream is the identity function and the stream built-ins (read-line, write-line, read-byte, write-byte, close) work on it directly.

Only TCP is supported: :protocol :datagram (UDP) signals an error. The other keyword arguments are accepted for compatibility and ignored -- :element-type in particular, because a rontolisp socket handle is always bidirectional and supports both the line and the byte built-ins (there is no separate binary/character stream construction to select).

The cl-postgres (Postmodern) connection shape works verbatim:

(usocket:socket-stream
 (usocket:socket-connect "localhost" 5432
                         :element-type '(unsigned-byte 8)))

A loopback echo round trip (single-threaded choreography: connect before accept, write before the peer reads):

The usocket package is loaded automatically on first use (interpreter) or spliced into the compiled program (JVM / WASM component), and is also registered as the built-in ASDF system "usocket", so (asdf:load-system "usocket"), (ql:quickload :usocket) and a third-party .asd's :depends-on ("usocket") all resolve to it without touching the network. rontolisp has no condition system, so usocket:socket-error and the other condition types exist as data symbols only -- a connection failure signals an error (interpreter / JVM) or returns nil (WASM component), and handler-case over usocket conditions is not supported.

Backend support

• Interpreter and JVM: full support (delegates to rontolisp:tcp-connect).
• WASM: component mode only (--component), IPv4 literals only; a failed connection returns nil. Preview 1 is a compile error.
• Browser playground: not supported.