Example of HTTP GET request in SML

getreq.sml

(*
 * Tested on Poly/ML.
 * Usage:
 *     $ polyc getreq.sml
 *     $ ./a.out
 *)

exception E of string

fun request domain path =
    let
        val req = "GET " ^ path ^ " HTTP/1.1\r\nHost: " ^ domain ^ "\r\n\r\n";
        val vec = Byte.stringToBytes(req);
        val slice = Word8VectorSlice.slice(vec, 0, NONE);
        val socket = INetSock.TCP.socket ();
        val address =
            let
                val SOME entry = NetHostDB.getByName domain;
            in
                INetSock.toAddr (NetHostDB.addr entry, 80)
            end;
        val read = ref 0
        val rsp = ref ""
    in
        print (req);
        Socket.connect (socket, address);
        Socket.sendVec (socket, slice);
        while (!read > 0 orelse !rsp = "") do
            let
                val vec = Socket.recvVec (socket, 1024);
                val len = Word8Vector.length vec;
            in
                read := (if len < 1024 then 0 else 1);
                rsp := !rsp ^ Byte.bytesToString (vec)
            end;
        print (!rsp);
        Socket.close (socket)
    end

fun main () =
    request "api.ipify.org" "/"