How to define a function in ghci across multiple lines?

I'm trying to define any simple function that spans multiple lines in ghci, take the following as an example:

let abs n | n >= 0 = n
          | otherwise = -n

So far I've tried pressing Enter after the first line:

Prelude> let abs n | n >= 0 = n
Prelude>           | otherwise = -n
<interactive>:1:0: parse error on input `|'

I've also attempted to use the :{ and :} commands but I don't get far:

Prelude> :{
unknown command ':{'
use :? for help.

I'm using GHC Interactive version 6.6 for Haskell 98 on Linux, what am I missing?

For guards (like your example), you can just put them all on one line and it works (guards do not care about spacing)

let abs n | n >= 0 = n | otherwise = -n

If you wanted to write your function with multiple definitions that pattern match on the arguments, like this:

fact 0 = 1
fact n = n * fact (n-1)

Then you would use braces with semicolons separating the definitions

let { fact 0 = 1 ; fact n = n * fact (n-1) }