Neat! /me is going to love :grep and :redir All these are for playing with the debugger. -- running main in tracing mode *Main> :main arg1 arg2 ... *Main> :maintraced arg1 arg2 ... -- stepping into main *Main> :mainstep arg1 arg2 ... -- eval to whnf Prelude> let li = map Just [1..3] Prelude> :sp li li = _ Prelude> :eval li () Prelude> :sp li li = _ : _ On 08/09/2007, at 3:30, Claus Reinke wrote:
having only recently started to play with ghci's :def and :cmd, i'm still in the process of figuring out what is and what isn't possible, and i've been wondering what wonderful things other ghci users have in their .ghci files? to start with, here are my current favourites (definitions attached, this is using a recent ghc 6.7). i'm looking forward to seeing your gems and favourites:-)
-- capturing command output in variables: *Main> :redir out :info Monad *Main> putStrLn out 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 [] -- Defined in GHC.Base instance Monad IO -- Defined in GHC.IOBase
-- filtering command output for lines matching pattern: *Main> :grep break :?
:abandon at a breakpoint, abandon current computation :break [<mod>] <l> [<col>] set a breakpoint at the specified location :break <name> set a breakpoint on the specified function :continue resume after a breakpoint :delete <number> delete the specified breakpoint :delete * delete all breakpoints :step single-step after stopping at a breakpoint :trace trace after stopping at a breakpoint :trace <expr> trace into <expr> (remembers breakpoints for :history) :set stop <cmd> set the command to run when a breakpoint is hit :show breaks show the active breakpoints :show context show the breakpoint context
*Main> :grep class :browse Control.Monad
class Monad m where class Functor f where fmap :: (a -> b) -> f a -> f b class (Monad m) => MonadPlus m where
-- Hugs' :find <id>, calling editor to open definition of <id> *Main> :find main
probably, there should be a wiki page collecting such :definitions, and other ways of improving the ghci usage experience. but i'm unsure whether to add to the haskell wiki
http://haskell.org/haskellwiki/GHC/GHCi
or to the ghc developer's wiki
http://hackage.haskell.org/trac/ghc
opinions? suggestions? tips? tricks?-) claus
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