Documentation

Reads one line of input. The final newline (if any) is removed. When using terminal-style interaction, this function provides a rich line-editing user interface.

If autoAddHistory == True and the line input is nonblank (i.e., is not all spaces), it will be automatically added to the history.

Reads one line of input and fills the insertion space with initial text. When using terminal-style interaction, this function provides a rich line-editing user interface with the added ability to give the user default values.

This function behaves in the exact same manner as getInputLine, except that it pre-populates the input area. The text that resides in the input area is given as a 2-tuple with two Strings. The string on the left of the tuple (obtained by calling fst) is what will appear to the left of the cursor and the string on the right (obtained by calling snd) is what will appear to the right of the cursor.

Some examples of calling of this function are:

getInputLineWithInitial "prompt> " ("left", "") -- The cursor starts at the end of the line.
getInputLineWithInitial "prompt> " ("left ", "right") -- The cursor starts before the second word.

Reads one character of input. Ignores non-printable characters.

When using terminal-style interaction, the character will be read without waiting for a newline.

When using file-style interaction, a newline will be read if it is immediately available after the input character.

Reads one line of input, without displaying the input while it is being typed. When using terminal-style interaction, the masking character (if given) will replace each typed character.

When using file-style interaction, this function turns off echoing while reading the line of input.

Note that if Haskeline is built against a version of the Win32 library earlier than 2.5, getPassword will incorrectly echo back input on MinTTY consoles (such as Cygwin or MSYS).

Waits for one key to be pressed, then returns. Ignores the value of the specific key.

Returns True if it successfully accepted one key. Returns False if it encountered the end of input; i.e., an EOF in file-style interaction, or a Ctrl-D in terminal-style interaction.

When using file-style interaction, consumes a single character from the input which may be non-printable.

Write a Unicode string to the user's standard output.

Write a Unicode string to the user's standard output, followed by a newline.

If Ctrl-C is pressed during the given action, enables interrupt handling within the nested scope. For example:

tryAction :: Eff '[Readline, HandleInterrupt] m => m ()
tryAction = handleInterrupt (outputStrLn "Cancelled.")
               $ withInterrupt $ someLongAction

The action can handle the interrupt itself every time Ctrl-C is pressed.

{-# LANGUAGE -XBlockArguments #-}
tryAction :: Eff '[Readline, HandleInterrupt] m => m ()
tryAction = withInterrupt loop where
  loop = someLongAction `catchInterrupt` do
    outputStrLn "Cancelled; trying again."
    loop

This behavior differs from GHC's built-in Ctrl-C handling, which may immediately terminate the program after the second time that the user presses Ctrl-C.

Handle an Interrupt. When an interrupt occurs in the second argument, the first argument will be called.

Specify a continuation that should be called when an Interrupt occurs.

catchInterrupt = flip handleInterrupt

Get the History.

Set the History.

Modify the History. The modification is not atomic.

newtype that provides MonadIO when Eff (Embed IO) m and otherwise just passes through instances to the base monad

Version of InputT that we "own" so that we can define new instances on it, in particular threading constraints without creating orphan instances.

Threading constraint for handlers using InputT/ReadlineT internally.

ReadlineThreads accepts all the primitive effects (intended to be used as such) offered by in-other-words.

Most notably, ReadlineThreads accepts Unlift b.

Type for denoting which kind of Optional we are inside of.

Main interpreter for Readline, ReadlineHistory, and HandleInterrupt effects. defaultSettings exists as a default for settings.

Example usage:

import Control.Effect
import Control.Effect.Readline

repl :: Effs '[Readline, HandleInterrupt] m => m ()
repl = handleInterrupt (outputStrLn "Interrupt!" *> repl) $
  withInterrupt $ do
    mline <- getInputLine "> "
    case mline of
      Nothing -> pure ()
      Just line -> outputStrLn line *> repl

main :: IO ()
main = runM $ runReadline defaultSettings repl

Like runReadline but additionally allows specifying a Behavior.

Like runReadline but additionally allows specifying a Prefs.

Like runReadline but additionally allows specifying a Behavior and a Prefs.

Weaker version of runReadline intended for circumstances where the primitive effect Optional can't be threaded. This version is incapable of interpreting HandleInterrupt though.

Weaker version of runReadlineBehavior intended for circumstances where the primitive effect Optional can't be threaded. This version is incapable of interpreting HandleInterrupt though.

Weaker version of runReadlineWithPrefs intended for circumstances where the primitive effect Optional can't be threaded. This version is incapable of interpreting HandleInterrupt though.

Weaker version of runReadlineBehaviorWithPrefs intended for circumstances where the primitive effect Optional can't be threaded. This version is incapable of interpreting HandleInterrupt though.