Prelude> :type (+)
(+) :: Num a => a -> a -> a

Prelude> :type 1
1 :: Num a => a

Prelude> (+) 2<interactive>:35:1:No instance for (Num a0) arising from a use of `+'The type variable `a0' is ambiguousPossible fix: add a type signature that fixes these type variable(s)Note: there are several potential instances:instance Num Double -- Defined in `GHC.Float'instance Num Float -- Defined in `GHC.Float'instance Integral a => Num (GHC.Real.Ratio a)-- Defined in `GHC.Real'...plus three othersIn the expression: (+) 2In an equation for `it': it = (+) 2<interactive>:35:1:No instance for (Show (a0 -> a0)) arising from a use of `print'Possible fix: add an instance declaration for (Show (a0 -> a0))In a stmt of an interactive GHCi command: print it
Prelude> :type (+) 2
(+) 2 :: Num a => a -> a

Prelude> :type +<interactive>:1:1: parse error on input `+'
Prelude> :type (+)
(+) :: Num a => a -> a -> a
Prelude> :type names
names :: [Char]
Prelude> :type head
head :: [a] -> a
Prelude> :type (head)
(head) :: [a] -> a

Prelude> :type map
map :: (a -> b) -> [a] -> [b]

Prelude> let nums = [1..100]
Prelude> map ((*) 2) nums
[2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,98,100,102,104,106,108,110,112,114,116,118,120,122,124,126,128,130,132,134,136,138,140,142,144,146,148,150,152,154,156,158,160,162,164,166,168,170,172,174,176,178,180,182,184,186,188,190,192,194,196,198,200]

Prelude> :helpCommands available from the prompt:<statement>                 evaluate/run <statement>:                           repeat last command:{\n ..lines.. \n:}\n       multiline command:add [*]<module> ...        add module(s) to the current target set:browse[!] [[*]<mod>]       display the names defined by module <mod>(!: more details; *: all top-level names):cd <dir>                   change directory to <dir>:cmd <expr>                 run the commands returned by <expr>::IO String:ctags[!] [<file>]          create tags file for Vi (default: "tags")(!: use regex instead of line number):def <cmd> <expr>           define command :<cmd> (later defined command hasprecedence, ::<cmd> is always a builtin command):edit <file>                edit file:edit                       edit last module:etags [<file>]             create tags file for Emacs (default: "TAGS"):help, :?                   display this list of commands:info [<name> ...]          display information about the given names:issafe [<mod>]             display safe haskell information of module <mod>:kind <type>                show the kind of <type>:load [*]<module> ...       load module(s) and their dependents:main [<arguments> ...]     run the main function with the given arguments:module [+/-] [*]<mod> ...  set the context for expression evaluation:quit                       exit GHCi:reload                     reload the current module set:run function [<arguments> ...] run the function with the given arguments:script <filename>          run the script <filename>:type <expr>                show the type of <expr>:undef <cmd>                undefine user-defined command :<cmd>:!<command>                 run the shell command <command>-- Commands for debugging::abandon                    at a breakpoint, abandon current computation:back                       go back in the history (after :trace):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:force <expr>               print <expr>, forcing unevaluated parts:forward                    go forward in the history (after :back):history [<n>]              after :trace, show the execution history:list                       show the source code around current breakpoint:list identifier            show the source code for <identifier>:list [<module>] <line>     show the source code around line number <line>:print [<name> ...]         prints a value without forcing its computation:sprint [<name> ...]        simplifed version of :print:step                       single-step after stopping at a breakpoint:step <expr>                single-step into <expr>: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 <expr>               evaluate <expr> with tracing on (see :history)-- Commands for changing settings::set <option> ...           set options:seti <option> ...          set options for interactive evaluation only:set args <arg> ...         set the arguments returned by System.getArgs:set prog <progname>        set the value returned by System.getProgName:set prompt <prompt>        set the prompt used in GHCi:set editor <cmd>           set the command used for :edit:set stop [<n>] <cmd>       set the command to run when a breakpoint is hit:unset <option> ...         unset optionsOptions 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-<flags>      most GHC command line flags can also be set here(eg. -v2, -fglasgow-exts, 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 modules               show the currently loaded modules:show packages              show the currently active package flags:show language              show the currently active language flags:show <setting>             show value of <setting>, which is one of[args, prog, prompt, editor, stop]:showi language             show language flags for interactive evaluation

Prelude> :show modules
Prelude> :show contextPrelude> :show bindings
names :: [Char] = "Daniel King"
nums :: [Integer] = 1 : 2 : 3 : 4 : 5 : ....
it :: [Integer] = 2 : 4 : 6 : 8 : 10 : ....
Prelude> :show imports
import Prelude -- implicit
Prelude> :show packages
active package flags: none
Prelude> :show languages
base language is: Haskell2010
with the following modifiers:-XNoDatatypeContexts-XNondecreasingIndentation

Prelude> foldl ((+)) 0 [1..100]
5050

Prelude> :type map
map :: (a -> b) -> [a] -> [b]
Prelude> :type filter
filter :: (a -> Bool) -> [a] -> [a]
Prelude> :type foldr
foldr :: (a -> b -> b) -> b -> [a] -> b
Prelude> :type foldl
foldl :: (a -> b -> a) -> a -> [b] -> a

Prelude> filter ((>) 50) nums
[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49]

Prelude> :type foldr
foldr :: (a -> b -> b) -> b -> [a] -> b
Prelude> foldr (:) "King" ['D','a','n','i','e','l', ' ']
"Daniel King"

Prelude> map Data.Char.isDigit ((++) ['0'..'9'] ['a'..'z'])
[True,True,True,True,True,True,True,True,True,True,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False]
Prelude> map Data.Char.isDigit (concat [['0'..'9'],['a'..'z']])
[True,True,True,True,True,True,True,True,True,True,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False,False]