About Lambdabot
Lambdabot is an IRC bot written over several years by those on the Freenode
#haskell IRC channel.
It operates as a command line tool, embedded in an editor, embedded in GHCi,
via internet relay chat and on the web.
Installation
The easiest way to install lambdabot is from hackage, by the following
commands:
cabal install --constraint 'transformers installed' lambdabot djinn
hoogle data
The second command fetches the data for Lambdabot’s @hoogle command, which
is a thin wrapper around the hoogle
command line tool. Invoking lambdabot will (hopefully) display a
lambdabot> prompt.
It is also possible to install lambdabot in a sandbox. In that case, use
cabal exec lambdabot to launch lambdabot.
Files
Some lambdabot modules maintain state. The state is stored in ./State/
if that directory exits; otherwise, it will end up on ~/.lambdabot/State/.
State files of particular interest are:
Pristine.hs and L.hs: Environment for running Haskell code.
The command @let adds new definitions to L.hs, whereas @undefine
copies Pristine.hs to L.hs.offlinerc: This file contains a history of commands typed into
lambdabot’s tty interface.
Customization
The state file Pristine.hs defines the environment in which Haskell code
is run. To customize lambdabot’s modules, unpack the lambdabot package
cabal unpack lambdabot; cd lambdabot-<version>
You can then edit src/Modules.hs to configure the loaded modules.
Using Lambdabot
Lambdabot has a number of modules, most of which provide several commands.
Type @listmodules to obtain a list of module names, and then
@list <module> to list a module’s commands. Executing @help command
displays a short description of the command.
The following sample session demonstrates some useful lambdabot commands.
lambdabot> > sum [1..10]
55
lambdabot> @let foo = 42
lambdabot> > product [1..foo]
1405006117752879898543142606244511569936384000000000
lambdabot> @undefine
Not in scope:‘foo’
Perhaps you meant ‘Data.Traversable.for’ (imported from Data.Traversable)
lambdabot> @type map
(a -> b) -> [a] -> [b]
lambdabot> @djinn (b -> c) -> (a -> b) -> a -> c
f a b c = a (b c)
lambdabot> @pl \x y z -> y z x
flip flip
lambdabot> @unpl flip flip
(\ b c f -> c f b)
lambdabot> @undo do x <- step1; step2; step3
step1 >>= \ x -> step2 >> step3
Further Information
