How do I enable language extensions from within GHCi?

I'm trying to enable XRankNTypes in GHCi. How do I do this?

Solution

:set -XRankNTypes. The -X part is a compiler switch, by the way, extension is called just RankNTypes.

Difference between GHC's -O and -O2
How to combine case statement patterns
(How) can I get the character that is currently shown at a given position in the terminal?
What exactly is meant by "partial function" in functional programming?
How to access an external package in a file
Attempting lens/traversal map multi-update on a subset of its keys
Efficient connected components from a 2D array
Haskell GHC: what is the time complexity of a pattern match with N constructors?
Dependent shrinking in QuickCheck
How to efficiently make ASCII art in terminal with Haskell?
Use type classes to implement dependency inversion in a Haskell application?
What happens to you if you break the monad laws?
DFS-compatible coordinate-free neighbors in Haskell
Haskell pattern matching on a list of lists - why doesn't this work?
How to convert Map.adjust to monadic?
Good, small Haskell compiler for linux?
How, why and when to use the ".Internal" modules pattern?
Why does Haskell's `transpose` function in Data.List not use `head` and `tail`?
Haskell: same module found twice - "Ambiguous module name"
Why does printf not work with ccall in haskell?
How would I make GHC.Ptr an instance of Monad?
Parsec how to find "matches" within a string
What is the kind of the function arrow in haskell?
Applications of polymorphic recursion
Haskell function return arguments for other function
How to get a Drawable or DrawWindow from a DrawingArea in Haskell Gtk2Hs Gtk3
What does this list permutations implementation in Haskell exactly do?
How can I concisely modify a record's field?
How do I read what's in a binary tree in Haskell?
Implement insert in haskell with foldr