Safe Haskell | None |
---|---|
Language | Haskell98 |
This is a shell monad, for generating shell scripts.
- data Script a
- script :: Script f -> Text
- linearScript :: Script f -> Text
- data Var
- val :: Var -> Quoted Text
- data Quoted a
- quote :: Text -> Quoted Text
- glob :: Text -> Quoted Text
- run :: Text -> [Text] -> Script ()
- cmd :: (Param command, CmdParams params) => command -> params
- class Param a
- class CmdParams t
- newtype Output = Output (Script ())
- newtype Val v = Val v
- comment :: Text -> Script ()
- newtype NamedLike = NamedLike Text
- class NameHinted h
- newVar :: NameHinted namehint => namehint -> Script Var
- newVarContaining :: NameHinted namehint => Text -> namehint -> Script Var
- globalVar :: Text -> Script Var
- positionalParameters :: Var
- takeParameter :: NameHinted namehint => namehint -> Script Var
- func :: (NameHinted namehint, CmdParams callfunc) => namehint -> Script () -> Script callfunc
- forCmd :: Script () -> (Var -> Script ()) -> Script ()
- whileCmd :: Script () -> Script () -> Script ()
- ifCmd :: Script () -> Script () -> Script () -> Script ()
- whenCmd :: Script () -> Script () -> Script ()
- unlessCmd :: Script () -> Script () -> Script ()
- readVar :: Var -> Script ()
- stopOnFailure :: Bool -> Script ()
- ignoreFailure :: Script () -> Script ()
- (-|-) :: Script () -> Script () -> Script ()
- (-&&-) :: Script () -> Script () -> Script ()
- (-||-) :: Script () -> Script () -> Script ()
- class RedirFile r
- (|>) :: RedirFile f => Script () -> f -> Script ()
- (|>>) :: RedirFile f => Script () -> f -> Script ()
- (|<) :: RedirFile f => Script () -> f -> Script ()
- toStderr :: Script () -> Script ()
- (|>&) :: (Script (), Fd) -> Fd -> Script ()
- (|<&) :: (Script (), Fd) -> Fd -> Script ()
- (->-) :: Script () -> Fd -> (Script (), Fd)
- hereDocument :: Script () -> Text -> Script ()
Documentation
Shell script monad.
script :: Script f -> Text Source
Generates a shell script, including hashbang, suitable to be written to a file.
linearScript :: Script f -> Text Source
Generates a single line of shell code.
A shell variable.
A value that is safely quoted.
quote :: Text -> Quoted Text Source
Quotes the Text to allow it to be safely exposed to the shell.
The method used is to replace ' with '"'"' and wrap the value inside single quotes. This works for POSIX shells, as well as other shells like csh.
glob :: Text -> Quoted Text Source
Treats the Text as a glob, which expands to one parameter per matching file.
The input is assumed to be a well-formed glob. Characters in it that are not alphanumeric and are not wildcard characters will be escaped before it is exposed to the shell. This allows eg, spaces in globs.
cmd :: (Param command, CmdParams params) => command -> params Source
Variadic and polymorphic version of run
A command can be passed any number of Params.
demo = script $ do cmd "echo" "hello, world" name <- newVar "name" readVar name cmd "echo" "hello" name
For the most efficient use of cmd
, add the following boilerplate,
which will make string literals in your program default to being Text:
{-# LANGUAGE OverloadedStrings, ExtendedDefaultRules #-} {-# OPTIONS_GHC -fno-warn-type-defaults #-} import Control.Monad.Shell import qualified Data.Text.Lazy as L default (L.Text)
Note that the command to run is itself a Param, so it can be a Text, or a String, or even a Var or Output. For example, this echos "hi":
demo = script $ do echovar <- newVarContaining "echo" () cmd echovar "hi"
A Param is anything that can be used as the parameter of a command.
toTextParam
Param String | String arguments are automatically quoted. |
Param Text | Text arguments are automatically quoted. |
Param Output | Allows passing the output of a command as a parameter. |
Param Var | Var arguments cause the (quoted) value of a shell variable to be passed to the command. |
Show v => Param (Val v) | Any value that can be shown can be passed to |
Param (Quoted Text) | Quoted Text arguments are passed as-is. |
Allows a function to take any number of Params.
cmdAll
The output of a command, or even a more complicated Script
can be passed as a parameter to cmd
Examples:
cmd "echo" "hello there," (Output (cmd "whoami")) cmd "echo" "root's pwent" (Output (cmd "cat" "/etc/passwd" -|- cmd "grep" "root"))
An arbitrary value.
Val v |
Suggests that a shell variable or function have its name contain the specified Text.
class NameHinted h Source
Class of values that provide a hint for the name to use for a shell variable or function.
To skip providing a hint, use '()'. To provide a hint, use '(NamedLike "name")'.
hinted
newVar :: NameHinted namehint => namehint -> Script Var Source
Defines a new shell variable.
Each call to newVar will generate a new, unique variable name.
The namehint can influence this name, but is modified to ensure uniqueness.
newVarContaining :: NameHinted namehint => Text -> namehint -> Script Var Source
Creates a new shell variable, with an initial value.
positionalParameters :: Var Source
This special Var expands to whatever parameters were passed to the shell script.
Inside a func, it expands to whatever parameters were passed to the func.
(This is $@
in shell)
takeParameter :: NameHinted namehint => namehint -> Script Var Source
Takes the first positional parameter, removing it from positionalParameters and returning a new Var that holds the value of the parameter.
If there are no more positional parameters, the script will crash with an error.
For example:
removefirstfile = script $ do cmd "rm" =<< takeParameter cmd "echo" "remaining parameters:" positionalParameters
func :: (NameHinted namehint, CmdParams callfunc) => namehint -> Script () -> Script callfunc Source
Defines a shell function, and returns an action that can be run to call the function.
The action is variadic; it can be passed any number of CmdParams. Typically, it will make sense to specify a more concrete type when defining the shell function.
The shell function will be given a unique name, that is not used by any other shell function. The namehint can be used to influence the contents of the function name, which makes for more readable generated shell code.
For example:
demo = script $ do hohoho <- mkHohoho hohoho (Val 1) echo "And I heard him exclaim, ere he rode out of sight ..." hohoho (Val 3) mkHohoho :: Script (Val Int -> Script ()) mkHohoho = func (NamedLike "hohoho") $ do num <- takeParameter forCmd (cmd "seq" "1" num) $ \_n -> cmd "echo" "Ho, ho, ho!" "Merry xmas!"
forCmd :: Script () -> (Var -> Script ()) -> Script () Source
Runs the command, and separates its output into parts (using the IFS)
The action is run for each part, passed a Var containing the part.
whileCmd :: Script () -> Script () -> Script () Source
As long as the first Script exits nonzero, runs the second script.
ifCmd :: Script () -> Script () -> Script () -> Script () Source
if with a monadic conditional
If the conditional exits 0, the first action is run, else the second.
readVar :: Var -> Script () Source
Generates shell code to fill a variable with a line read from stdin.
stopOnFailure :: Bool -> Script () Source
By default, shell scripts continue running past commands that exit nonzero. Use "stopOnFailure True" to make the script stop on the first such command.
ignoreFailure :: Script () -> Script () Source
Makes a nonzero exit status be ignored.
Any function that takes a RedirFile can be passed a a FilePath, in which case the default file descriptor will be redirected to/from the FilePath.
Or, it can be passed a tuple of (Fd, FilePath), in which case the specified Fd will be redirected to/from the FilePath.
fromRedirFile
(|>) :: RedirFile f => Script () -> f -> Script () Source
Redirects to a file, overwriting any existing file.
For example, to shut up a noisy command:
cmd "find" "/" |> "/dev/null"
(|>>) :: RedirFile f => Script () -> f -> Script () Source
Appends to a file. (If file doesn't exist, it will be created.)
(|>&) :: (Script (), Fd) -> Fd -> Script () Source
Redirects the first file descriptor to output to the second.
For example, to redirect a command's stderr to stdout:
cmd "foo" ->- stdError) |>& stdOutput
(|<&) :: (Script (), Fd) -> Fd -> Script () Source
Redirects the first file descriptor to input from the second.
hereDocument :: Script () -> Text -> Script () Source
Provides the Text as input to the Script, using a here-document.