# Cookbook/Compilers and interpreters

From HaskellWiki

## GHC

TODO

## GHCi

Problem | Solution | Examples |
---|---|---|

checking definitions | :i | ```
Prelude> :i Monad
class Monad m where
(>>=) :: m a -> (a -> m b) -> m b
(>>) :: m a -> m b -> m b
return :: a -> m a
fail :: String -> m a
-- Defined in GHC.Base
instance Monad Maybe -- Defined in Data.Maybe
instance Monad IO -- Defined in GHC.IOBase
instance Monad ((->) r) -- Defined in Control.Monad.Instances
instance Monad [] -- Defined in GHC.Base
``` |

checking types | :t | ```
Prelude> :t "Hello"
"Hello" :: [Char]
Prelude> :t length
length :: [a] -> Int
``` |

## Hugs

TODO