Building the Socket Addon for Io

November 4th, 2009

I have had this draft sitting on the back-burner for a while now, and yesterday's post encouraged me to finish this one. If more than just the Socket addon is broken in your install of Io, you may try following these alternative instructions for building Io and all of the addons.

I stumbled upon the Io language the other day after following a long list of links that started with my reading Paul Graham's list of accumulator-generators in various programming languages. To quote the official Io website verbatim:

Io is a small, prototype-based programming language. Io is inspired by Smalltalk (all values are objects, all messages are dynamic), Self (prototype-based), NewtonScript (differential inheritance), Act1 (actors and futures for concurrency), LISP (code is a runtime inspectable/modifiable tree) and Lua (small, embeddable).

However, what really grabbed my attention was the bits of philosophy from Perspective — Why Another Programming:

The focus of programming language research for the last thirty years has been to combine the expressive power of high level languages like Smalltalk and the performance of low level language like C with little attention paid to advancing expressive power itself. The result has been a series of languages which are neither as fast as C or as expressive as Smalltalk. Io's purpose is to refocus attention on expressiveness by exploring higher level dynamic programming features with greater levels of runtime flexibility and simplified programming syntax and semantics.

It was easy to follow the guide from the docs on building and installing Io, but most of the addons didn't come out the other end of the process. Socket in particular was giving me this exception in the Io interpreter/REPL:

Io> Socket

Exception: Failed to load Addon Socket - it appears that the addon exists but
was not compiled. You might try running 'make Socket' in the Io source folder.
---------
Object Socket                        Command Line 1

First of all, thanks to all the kind people on the mailing list, and especially jer on #io, I was able to get the Socket addon working. In case anyone else has this same issue, I have gone back through the troubleshooting sessions and derived exactly what was causing the problem, and made some instructions on how to fix it cleanly.

Summary

1. Remove all versions of and references to libevent from your system
2. Build and install libevent-1.4.8-stable from source
3. Rebuild and reinstall Io

Remove all versions of and references to libevent from your system

sudo aptitude remove libevent and similar commands (depending on your version of libevent and package manager) did not completely remove it for me and this was causing issues. I think I ran something like locate libevent | xargs sudo rm to completely remove everything, but it felt like a shady command to run then, and it still does now. Hopefully you have access to someone with more nix experience than me that can give you a better command to remove libevent completely.

Build and install libevent-1.4.8-stable from source [1]

Grab the gzipped tar package

$ wget http://monkey.org/~provos/libevent-1.4.8-stable.tar.gz

and run each the following commands in order.

$ gzip -d libevent-1.4.8-stable.tar.gz && tar -xf libevent-1.4.8-stable.tar && rm libevent-1.4.8-stable.tar
$ cd libevent-1.4.8-stable
$ ./configure --prefix=/usr
$ sudo make

Now run

$ sudo checkinstall -D

which should prompt you for a description, use "libevent". Next, you will be at the main menu for checkinstall. Press "2" to change the name of the package to plain old "libevent", then press "3" to change the version number from "stable" to "1.4.8". Hit enter from the main menu to let checkinstall finish the installation for you.

Rebuild and reinstall Io

Call directory back to the dir that has your Io source code and finish up with

$ sudo make clean
$ sudo make
$ sudo make install

Go ahead and open up the Io REPL and test out Socket!

Io> Socket
==>  Socket_0x91d7f10:
  acceptTimeout    = 31536000
  appendToWriteBuffer = method(buffer, ...)
  asyncAccept      = Socket_asyncAccept()
  asyncBind        = Socket_asyncBind()
  asyncConnect     = Socket_asyncConnect()
  asyncListen      = Socket_asyncListen()
  asyncStreamOpen  = Socket_asyncStreamOpen()
  asyncStreamRead  = Socket_asyncStreamRead()
  asyncStreamWrite = Socket_asyncStreamWrite()
  asyncUdpOpen     = Socket_asyncUdpOpen()
  asyncUdpRead     = Socket_asyncUdpRead()
  asyncUdpWrite    = Socket_asyncUdpWrite()
  bytesPerRead     = 4096
  bytesPerWrite    = 1024
  close            = Socket_close()
  connect          = method(...)
  connectTimeout   = 60
  descriptorId     = Socket_descriptorId()
  errorDescription = Socket_errorDescription()
  errorNumber      = Socket_errorNumber()
  getSocketReadLowWaterMark = Socket_getSocketReadLowWaterMark()
  getSocketWriteLowWaterMark = Socket_getSocketWriteLowWaterMark()
  host             = method(...)
  init             = method(...)
  ipAddress        = 0.0.0.0:0
  isOpen           = Socket_isOpen()
  isStream         = Socket_isStream()
  isSynchronous    = false
  isValid          = Socket_isValid()
  port             = method(...)
  readBytes        = method(numBytes, ...)
  readListMessage  = method(...)
  readMessage      = method(...)
  readTimeout      = 60
  readUntilSeq     = method(aSeq, ...)
  serverOpen       = method(...)
  serverWaitForConnection = method(...)
  setAcceptTimeout = method(...)
  setBytesPerRead  = method(...)
  setBytesPerWrite = method(...)
  setConnectTimeout = method(...)
  setHost          = method(ip, ...)
  setIpAddress     = method(...)
  setIsSynchronous = method(...)
  setNoDelay       = Socket_setNoDelay()
  setPort          = method(port, ...)
  setReadTimeout   = method(...)
  setSocketReadBufferSize = Socket_setSocketReadBufferSize()
  setSocketReadLowWaterMark = Socket_setSocketReadLowWaterMark()
  setSocketWriteBufferSize = Socket_setSocketWriteBufferSize()
  setSocketWriteLowWaterMark = Socket_setSocketWriteLowWaterMark()
  setSyncWaitTime  = method(...)
  setWriteTimeout  = method(...)
  streamOpen       = method(...)
  streamRead       = method(numBytes, ...)
  streamReadNextChunk = method(...)
  streamReadWhileOpen = method(...)
  streamWrite      = method(buffer, writeCallback, ...)
  syncConnect      = method(...)
  syncStreamRead   = method(numBytes, ...)
  syncStreamReadNextChunk = method(...)
  syncStreamReadWhileOpen = method(...)
  syncUdpReadNextChunk = method(...)
  syncWait         = method(...)
  syncWaitTime     = 0.05
  syncWriteFromBuffer = method(writeCallback, ...)
  udpOpen          = method(...)
  udpRead          = method(ipAddress, numBytes, ...)
  udpReadNextChunk = method(ipAddress, ...)
  udpWrite         = Socket_asyncUdpWrite()
  writeFromBuffer  = method(writeCallback, ...)
  writeListMessage = method(aList, ...)
  writeMessage     = method(aSeq, ...)
  writeTimeout     = 60

Congratulations! Go have fun with Io!

References

1. The instructions on building libevent were taken from http://blog.as.tl/2009/01/04/compiling-io-on-ubuntu-810/.
2. The original topic I created on the Io language mailing list: Help with building the Socket addon please

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