Preston Lee's Blog

Tag: gem

  • Prolog for Ruby (ruby-prolog) Updated, Hits v1.0.1

    After a long period of inactivity I’ve updated the F/OSS ruby-prolog gem! It’s been updated for ruby 2.0.0, bundler, and minitest, and released as v1.0.1!

    ruby-prolog allows you to solve complex logic problems on the fly using a dynamic, Prolog-like DSL. Basic use is encompassed by stating basic facts using your data, defining rules, and then asking questions. Why is this cool? Because ruby-prolog allows you to leave your normal object-oriented vortex on demand and step into the alternate reality of declarative languages.

    With ruby-prolog:

    • There are no classes.
    • There are no functions.
    • There are no variables.
    • There are no control flow statements.

    You can use all these wonder things — it’s still Ruby after all — but they’re not needed, and mainly useful for getting data and results into/out of the interpreter. Prolog still tends to be favored heavily in artificial intelligence and theorem proving applications and is still relevant to computer science curricula as well, so I hope this updated release proves useful to the Ruby community.

    Check out a simple ACL enforcement example or, for the daring, the ruby-prolog solution to the Tower’s of Hanoi problem!

     

  • Installing The MySQL Ruby Gem When Using The Official MySQL .dmg

    If you installed MySQL using the official .dmg package provided by MySQL AB/Sun and are trying to install the native MySQL gem, you’ll need to pass a bunch of flags to the gem install process to get the thing to compile. Try this..

    sudo gem install mysql — –with-mysql-config=/usr/local/mysql/bin/mysql_config

    ..if you still have issues (check your /opt/local/lib/ruby/gems/<ruby_ver>/gems/mysql-<gem_ver>/mkmf.log file), try this instead..

    sudo gem install mysql — –with-mysql-dir=/usr/local/mysql –with-mysql-include=/usr/local/mysql/include/ –with-mysql-lib=/usr/local/mysql/lib/ –with-mysql-config=/usr/local/mysql/bin/mysql_config

    Run `sudo gem install mysql` and definitely recheck the log file again as the gem install process sometimes reports false positives even if native components fail to install.