*Main> :?
 Commands available from the prompt:

                 evaluate/run 
   :                           repeat last command
   :{\n ..lines.. \n:}\n       multiline command
   :add [*] ...        add module(s) to the current target set
   :browse[!] [[*]]       display the names defined by module 
                               (!: more details; *: all top-level names)
   :cd                    change directory to 
   :cmd                  run the commands returned by ::IO String
   :complete  []  list completions for partial input string
   :ctags[!] []          create tags file for Vi (default: "tags")
                               (!: use regex instead of line number)
   :def            define command : (later defined command has
                               precedence, :: is always a builtin command)
   :edit                 edit file
   :edit                       edit last module
   :etags []             create tags file for Emacs (default: "TAGS")
   :help, :?                   display this list of commands
   :info[!] [ ...]       display information about the given names
                               (!: do not filter instances)
   :issafe []             display safe haskell information of module 
   :kind[!]              show the kind of 
                               (!: also print the normalised type)
   :load [*] ...       load module(s) and their dependents
   :main [ ...]     run the main function with the given arguments
   :module [+/-] [*] ...  set the context for expression evaluation
   :quit                       exit GHCi
   :reload                     reload the current module set
   :run function [ ...] run the function with the given arguments
   :script           run the script 
   :type                 show the type of 
   :undef                 undefine user-defined command :
   :!                 run the shell command 

 -- Commands for debugging:

   :abandon                    at a breakpoint, abandon current computation
   :back                       go back in the history (after :trace)
   :break []  []  set a breakpoint at the specified location
   :break                set a breakpoint on the specified function
   :continue                   resume after a breakpoint
   :delete             delete the specified breakpoint
   :delete *                   delete all breakpoints
   :force                print , forcing unevaluated parts
   :forward                    go forward in the history (after :back)
   :history []              after :trace, show the execution history
   :list                       show the source code around current breakpoint
   :list           show the source code for 
   :list []      show the source code around line number 
   :print [ ...]         show a value without forcing its computation
   :sprint [ ...]        simplified version of :print
   :step                       single-step after stopping at a breakpoint
   :step                 single-step into 
   :steplocal                  single-step within the current top-level binding
   :stepmodule                 single-step restricted to the current module
   :trace                      trace after stopping at a breakpoint
   :trace                evaluate  with tracing on (see :history)

 -- Commands for changing settings:

   :set  ...           set options
   :seti  ...          set options for interactive evaluation only
   :set args  ...         set the arguments returned by System.getArgs
   :set prog         set the value returned by System.getProgName
   :set prompt         set the prompt used in GHCi
   :set prompt2        set the continuation prompt used in GHCi
   :set editor            set the command used for :edit
   :set stop []        set the command to run when a breakpoint is hit
   :unset  ...         unset options

  Options for ':set' and ':unset':

    +m            allow multiline commands
    +r            revert top-level expressions after each evaluation
    +s            print timing/memory stats after each evaluation
    +t            print type after evaluation
    -      most GHC command line flags can also be set here
                         (eg. -v2, -XFlexibleInstances, etc.)
                    for GHCi-specific flags, see User's Guide,
                    Flag reference, Interactive-mode options

 -- Commands for displaying information:

   :show bindings              show the current bindings made at the prompt
   :show breaks                show the active breakpoints
   :show context               show the breakpoint context
   :show imports               show the current imports
   :show linker                show current linker state
   :show modules               show the currently loaded modules
   :show packages              show the currently active package flags
   :show paths                 show the currently active search paths
   :show language              show the currently active language flags
   :show              show value of , which is one of
                                  [args, prog, prompt, editor, stop]
   :showi language             show language flags for interactive evaluation