Via command examples.
Example:
vim Specs.hs Ladder.hsSwitch to a file: :e Ladder.sh.
Horizontally:
vim Specs.hs Ladder.hs -OVertically:
vim Specs.hs Ladder.hs -oIf needed, enable it: :syntax on.
escape + u
:/wordToSearch then type n for next occurrence, shift + n for previous one.
Globally: :%s/replaceThisWord/withThisOne/g.
:x! saves all files and quits.
:x | !runhaskell Specs saves all files, quits and runs the command runhaskell Specs.
:q! quits without saving files.