The easiest way of installing Vala is to install your distribution-specific package.
On Ubuntu:
sudo apt install valac
On Fedora:
sudo dnf install vala
On Arch:
sudo pacman -S vala
On OS X, with Homebrew:
brew install vala
On Windows, you can get an installer for the latest version here.
You can also build it from sources, but you'll need to install pkg-config
, a C compiler, a standard C library and GLib 2 before:
wget https://download.gnome.org/sources/vala/0.34/vala-0.34.4.tar.xz
tar xvf vala-0.34.4.tar.xz
cd vala-0.34.4
./configure
make
sudo make install