the simplest and highest-level possible initialization of a server socket in Nim

easynetworking.nim

{.emit: """
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
""".}

type
  ServerSocket = distinct int
  ClientSocket = distinct int
  Port = distinct int16
  AddrInfo {.header: "<netdb.h>", importc: "struct addrinfo".} = object
  AddrInfoPtr = ptr AddrInfo

proc initServerSocket(port: Port): ServerSocket =
  var
    hints: AddrInfo
    res: AddrInfoPtr
    yes = 1
    strPort = $ int(port)
    
  {.emit: [hints, ".ai_family = AF_UNSPEC;"].}
  {.emit: [hints, ".ai_socktype = SOCK_STREAM;"].}
  {.emit: [hints, ".ai_flags = AI_PASSIVE;"].}
  {.emit: [ "getaddrinfo(NULL, ", cstring(strPort), ", ", addr(hints), ", ", addr(res), ");" ].}
  defer:
    {.emit: [ "freeaddrinfo(", res, ");" ].}

  {.emit: [ result, " = socket(", res, "->ai_family, ", res, "->ai_socktype, ", res, "->ai_protocol);" ].}
  if -1 == int(result): raise newException(IOError, "socket() failure")
  var iores: int
  {.emit: [ iores, " = setsockopt(", result, ", SOL_SOCKET, SO_REUSEADDR, ", addr(yes), ", ", sizeof(yes), ");" ].}
  if -1 == iores: raise newException(IOError, "setsockopt() failure")
  {.emit: [ iores, " = bind(", result, ", ", res, "->ai_addr, ", res, "->ai_addrlen);" ].}
  if -1 == iores: raise newException(IOError, "bind() failure")
  {.emit: [ iores, " = listen(", result, ", 4);" ].}

let serv = initServerSocket(Port(4001))