I recently purchased a MacBook Air in September for my birthday. One of the first things I noticed was that the operating system doesn’t show the ~/Library directory. It keeps annoying me, so after some researching I found the Terminal command to show hidden files. I put them into my aliases in my .zshrc which can be found in my fork of the Oh My Zsh! GitHub repository, but also posted them here for convenience.
These commands will either show/hide the hidden files and then relaunch Finder.app to show the changes.
alias show_hidden='defaults write com.apple.Finder AppleShowAllFiles YES && killall Finder && open /System/Library/CoreServices/Finder.app'
alias hide_hidden='defaults write com.apple.Finder AppleShowAllFiles NO && killall Finder && open /System/Library/CoreServices/Finder.app'