Example usage:

import Control.Break
import Control.Monad.State
import Prelude hiding (break)

example :: State Int ()
example = loop (do
    n <- lift get                -- Inside a `loop`, wrap commands in `lift`
    if n < 10
        then lift (put (n + 1))  -- You keep looping by default
        else break () )          -- Use `break` to exit from the `loop`

The loop command runs the given command repeatedly until the command breaks from the loop using break:

>>> execState example 0
10

For some effects (like State), you can omit lift:

example :: State Int ()
example = loop (do
    n <- get
    if n < 10
        then put (n + 1)
        else break () )

The loop will return whatever value you supply to break:

example :: State Int Bool
example = loop (do
    n <- get
    if n < 10
        then put (n + 1)
        else break True )

>>> runState example 0
(True,10)