Shelly

A module for shell-like / perl-like programming in Haskell. The stuff in here is not always pretty, but it gets the job done. The functionality provided by this module is (unlike standard Haskell filesystem functionality) thread-safe: each ShIO maintains its own environment and its own working directory.

Entering ShIO.

type ShIO a = ReaderT (IORef State) IO a

shelly :: MonadIO m => ShIO a -> m a

Enter a ShIO from (Monad)IO. The environment and working directories are inherited from the current process-wide values. Any subsequent changes in processwide working directory or environment are not reflected in the running ShIO.

sub :: ShIO a -> ShIO a

Enter a sub-ShIO that inherits the environment and working directory The original state will be restored when the sub-ShIO completes. Exceptions are propagated normally.

silently :: ShIO a -> ShIO a

Create a sub-ShIO in which external command outputs are not echoed. See sub.

verbosely :: ShIO a -> ShIO a

Create a sub-ShIO in which external command outputs are echoed. See sub.

print_commands :: ShIO a -> ShIO a

Create a sub-ShIO in which external command outputs are echoed. See sub.

Modifying and querying environment.

setenv :: Text -> Text -> ShIO ()

Set an environment variable. The environment is maintained in ShIO internally, and is passed to any external commands to be executed.

getenv :: Text -> ShIO Text

Fetch the current value of an environment variable. Both empty and non-existent variables give empty string as a result.

getenv_def :: Text -> Text -> ShIO Text

Fetch the current value of an environment variable. Both empty and non-existent variables give the default value as a result

appendPath :: FilePath -> ShIO ()

add the filepath onto the PATH env variable

Environment directory

cd :: FilePath -> ShIO ()

Change current working directory of ShIO. This does *not* change the working directory of the process we are running it. Instead, ShIO keeps track of its own workking directory and builds absolute paths internally instead of passing down relative paths. This may have performance repercussions if you are doing hundreds of thousands of filesystem operations. You will want to handle these issues differently in those cases.

chdir :: FilePath -> ShIO a -> ShIO a

cd, execute a ShIO action in the new directory and then pop back to the original directory

pwd :: ShIO FilePath

Obtain the current (ShIO) working directory.

Printing

echo, echo_n_err, echo_err, echo_n :: Text -> ShIO ()

Echo text to standard (error, when using _err variants) output. The _n variants do not print a final newline.

inspect :: Show s => s -> ShIO ()

a print lifted into ShIO

Querying filesystem.

ls :: FilePath -> ShIO [FilePath]

List directory contents. Does *not* include "." and "..", but it does include (other) hidden files.

ls' :: FilePath -> ShIO [Text]

Get back [Text] instead of [FilePath]

test_e :: FilePath -> ShIO Bool

Does a path point to an existing filesystem object?

test_f :: FilePath -> ShIO Bool

Does a path point to an existing file?

test_d :: FilePath -> ShIO Bool

Does a path point to an existing directory?

test_s :: FilePath -> ShIO Bool

Does a path point to a symlink?

which :: FilePath -> ShIO (Maybe FilePath)

Get a full path to an executable on PATH, if exists. FIXME does not respect setenv'd environment and uses PATH inherited from the process environment.

find :: FilePath -> ShIO [FilePath]

List directory recursively (like the POSIX utility find).

Filename helpers

path :: FilePath -> ShIO FilePath

makes an absolute path. Same as canonic. TODO: use normalise from system-filepath

absPath :: FilePath -> ShIO FilePath

makes an absolute path. path will also normalize

Manipulating filesystem.

mv :: FilePath -> FilePath -> ShIO ()

Currently a renameFile wrapper. TODO: Support cross-filesystem move. TODO: Support directory paths in the second parameter, like in cp.

rm_f :: FilePath -> ShIO ()

Remove a file. Does not fail if the file already is not there. Does fail if the file is not a file.

rm_rf :: FilePath -> ShIO ()

A swiss army cannon for removing things. Actually this goes farther than a normal rm -rf, as it will circumvent permission problems for the files we own. Use carefully.

cp :: FilePath -> FilePath -> ShIO ()

Copy a file. The second path could be a directory, in which case the original file name is used, in that directory.

cp_r :: FilePath -> FilePath -> ShIO ()

Copy a file, or a directory recursively.

mkdir :: FilePath -> ShIO ()

Create a new directory (fails if the directory exists).

mkdir_p :: FilePath -> ShIO ()

Create a new directory, including parents (succeeds if the directory already exists).

readfile :: FilePath -> ShIO Text

(Strictly) read file into a Text. All other functions use Lazy Text. So Internally this reads a file as strict text and then converts it to lazy text, which is inefficient

writefile :: FilePath -> Text -> ShIO ()

Write a Lazy Text to a file.

appendfile :: FilePath -> Text -> ShIO ()

Append a Lazy Text to a file.

withTmpDir :: (FilePath -> ShIO a) -> ShIO a

Create a temporary directory and pass it as a parameter to a ShIO computation. The directory is nuked afterwards.

Running external commands.

run :: FilePath -> [Text] -> ShIO Text

Execute an external command. Takes the command name (no shell allowed, just a name of something that can be found via PATH; FIXME: setenv'd PATH is not taken into account, only the one inherited from the actual outside environment). Nothing is provided on stdin of the process, and stdout and stderr are collected and stored. The stdout is returned as a result of run, and complete stderr output is available after the fact using lastStderr

All of the stdout output will be loaded into memory You can avoid this but still consume the result by using run', or if you need to process the output than runFoldLines

(#) :: FilePath -> [Text] -> ShIO Text

An infix shorthand for run. Write "command" # [ "argument" ... ].

run_ :: FilePath -> [Text] -> ShIO ()

(-|-) :: ShIO Text -> ShIO b -> ShIO b

set the output of the first command as the stdin of the second.

lastStderr :: ShIO Text

The output of last external command. See run.

setStdin :: Text -> ShIO ()

set the stdin to be used and cleared by the next run.

command :: FilePath -> [Text] -> [Text] -> ShIO Text

bind some arguments to run for re-use Example: monit = command monit [-c, monitrc]

command_ :: FilePath -> [Text] -> [Text] -> ShIO ()

bind some arguments to run_ for re-use Example: monit_ = command_ monit [-c, monitrc]

command1 :: FilePath -> [Text] -> Text -> [Text] -> ShIO Text

bind some arguments to run for re-use, and expect 1 argument Example: git = command1 git []; git pull [origin, master]

command1_ :: FilePath -> [Text] -> Text -> [Text] -> ShIO ()

bind some arguments to run for re-use, and expect 1 argument Example: git_ = command1_ git []; git+ pull [origin, master]

exiting the program

exit :: Int -> ShIO ()

errorExit :: Text -> ShIO ()

terror :: Text -> ShIO a

fail that takes a Text

Utilities.

(<$>) :: Functor f => (a -> b) -> f a -> f b

An infix synonym for fmap.

(<$$>) :: Functor m => (b -> c) -> (a -> m b) -> a -> m c

A functor-lifting function composition.

grep :: PredicateLike pattern hay => pattern -> [hay] -> [hay]

Like filter, but more conveniently used with String lists, where a substring match (TODO: also provide regexps, and maybe globs) is expressed as grep "needle" [ "the", "stack", "of", "hay" ]. Boolean predicates just like with filter are supported too: grep ("fun" isPrefixOf) [...].

whenM :: Monad m => m Bool -> m () -> m ()

A monadic-conditional version of the when guard.

unlessM :: Monad m => m Bool -> m () -> m ()

A monadic-conditional version of the unless guard.

canonic :: FilePath -> ShIO FilePath

Obtain a (reasonably) canonic file path to a filesystem object. Based on canonicalizePath in FileSystem.

catchany :: IO a -> (SomeException -> IO a) -> IO a

A helper to catch any exception (same as ... catch (e :: SomeException) -> ...).

catch_sh :: Exception e => ShIO a -> (e -> ShIO a) -> ShIO a

Catch an exception in the ShIO monad.

catchany_sh :: ShIO a -> (SomeException -> ShIO a) -> ShIO a

Catch an exception in the ShIO monad.

data MemTime

Constructors

MemTime Rational Double

Instances

Eq MemTime

Ord MemTime

Read MemTime

Show MemTime

time :: ShIO a -> ShIO (MemTime, a)

Run a ShIO computation and collect timing (TODO: and memory) information.

data RunFailed

Constructors

RunFailed FilePath [Text] Int Text

Instances

Show RunFailed

Typeable RunFailed

Exception RunFailed

mappend () Text with a FilePath

(|<>) :: FilePath -> Text -> Text

mappend a FilePath & Text. Warning: uses toTextUnsafe

(<>|) :: Text -> FilePath -> Text

mappend a Text & FilePath. Warning: uses toTextUnsafe

convert between Text and FilePath

toTextUnsafe :: FilePath -> Text

silently uses the Right or Left value of Filesystem.Path.CurrentOS.toText

toTextWarn :: FilePath -> ShIO Text

fromText :: Text -> FilePath

Re-exported for your convenience

liftIO :: MonadIO m => forall a. IO a -> m a

Lift a computation from the IO monad.

when :: Monad m => Bool -> m () -> m ()

Conditional execution of monadic expressions. For example,

       when debug (putStr "Debugging\n")

will output the string Debugging\n if the Boolean value debug is True, and otherwise do nothing.

unless :: Monad m => Bool -> m () -> m ()

The reverse of when.