To run Laravel 4.2 on a OS X Yosemite setup with the default PHP binary and Postgres as a database¹ you have to follow a few steps. Make sure you have Homebrew installed before you start.

Laravel needs the MCrypt PHP extension and since we want to use Postgres we also have to install the PDO Postgres driver.

php -v

Replace 55 within following commands with whatever version of PHP you are running.

brew tap josegonzalez/php
brew install php55-mcrypt --without-homebrew-php
brew install php55-pdo-pgsql --without-homebrew-php

Now we have to tell PHP about the new extensions. These paths depend on your installation so make sure to lookup the correct paths for your machine.

sudo cp /etc/php.ini.default /etc/php.ini
sudo echo 'extension="/usr/local/Cellar/php55-mcrypt/5.5.20/mcrypt.so"' >> /etc/php.ini
sudo echo 'extension="/usr/local/Cellar/php55-pdo-pgsql/5.5.20/pdo_pgsql.so"' >> /etc/php.ini

The next step is installing Composer so we can install Laravel and its dependencies. When adding the composer binary to your PATH make sure to adapt the path.

curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer
echo 'export PATH="/Users/david/.composer/vendor/bin:$PATH"' >> ~/.zshrc

Finally we can install Laravel itself and create a new project.

composer global require "laravel/installer=~1.1"
laravel new my-new-project