rontolisp:stream-read

(rontolisp:stream-read stream)

Returns a future settling to the stream's next chunk, or nil once the stream is closed and drained (end of stream). Chunks are never nil, so a nil result always means end of stream. A read on an open, empty stream stays pending until a write arrives — that is the suspension an awaiting asynchronous function parks on.

A chunk is whatever the producer wrote: a string for a guest-created stream, and an (unsigned-byte 8) vector for every HTTP body stream (a fetched reply's :body, a served request's :raw-body) — the octets exactly as they came off the wire, so a body relayed as a response body crosses byte-exact. rontolisp:read-all is the drain that decodes them to text.

"a"
NIL

To drain all remaining chunks into one string in one await, use rontolisp:read-all instead.

Backend support

Asynchronous streams exist on the interpreter, the JVM backend and -- for the request/response body streams rontolisp:fetch / rontolisp:http-handler produce -- the --component WASM backend. A Preview 1 WASM module can hold a stream value only when a host-backed body gives it one; where none can exist, rontolisp:streamp answers nil and rontolisp:stream-read / rontolisp:stream-close signal an error when called.