System.Console.Terminfo.Base

data Terminal Source

setupTerm :: String -> IO Terminal Source

Initialize the terminfo library to the given terminal entry.

Throws a SetupTermError if the terminfo database could not be read.

setupTermFromEnv :: IO Terminal Source

Initialize the terminfo library, using the TERM environmental variable. If TERM is not set, we use the generic, minimal entry dumb.

Throws a SetupTermError if the terminfo database could not be read.

data SetupTermError Source

data Capability a Source

A feature or operation which a Terminal may define.

getCapability :: Terminal -> Capability a -> Maybe a Source

tiGetFlag :: String -> Capability Bool Source

Look up a boolean capability in the terminfo database.

Unlike tiGuardFlag, this capability never fails; it returns False if the capability is absent or set to false, and returns True otherwise.

tiGuardFlag :: String -> Capability () Source

Look up a boolean capability in the terminfo database, and fail if it's not defined.

tiGetNum :: String -> Capability Int Source

Look up a numeric capability in the terminfo database.

tiGetStr :: String -> Capability String Source

Look up a string capability in the terminfo database. NOTE: This function is deprecated; use tiGetOutput1 instead.

Terminfo contains many string capabilities for special effects. For example, the cuu1 capability moves the cursor up one line; on ANSI terminals this is accomplished by printing the control sequence "\ESC[A". However, some older terminals also require "padding", or short pauses, after certain commands. For example, when TERM=vt100 the cuu1 capability is "\ESC[A$<2>", which instructs terminfo to pause for two milliseconds after outputting the control sequence.

The TermOutput monoid abstracts away all padding and control sequence output. Unfortunately, that datatype is difficult to integrate into existing String-based APIs such as pretty-printers. Thus, as a workaround, tiGetOutput1 also lets us access the control sequences as Strings. The one caveat is that it will not allow you to access padded control sequences as Strings. For example:

> t <- setupTerm "vt100"
> isJust (getCapability t (tiGetOutput1 "cuu1") :: Maybe String)
False
> isJust (getCapability t (tiGetOutput1 "cuu1") :: Maybe TermOutput)
True

String capabilities will work with software-based terminal types such as xterm and linux. However, you should use TermOutput if compatibility with older terminals is important. Additionally, the visualBell capability which flashes the screen usually produces its effect with a padding directive, so it will only work with TermOutput.

tiGetOutput1 :: forall f. OutputCap f => String -> Capability f Source

Look up an output capability which takes a fixed number of parameters (for example, Int -> Int -> TermOutput).

For capabilities which may contain variable-length padding, use tiGetOutput instead.

class OutputCap f Source

class (Monoid s, OutputCap s) => TermStr s Source

data TermOutput Source

An action which sends output to the terminal. That output may mix plain text with control characters and escape sequences, along with delays (called "padding") required by some older terminals.

runTermOutput :: Terminal -> TermOutput -> IO () Source

Write the terminal output to the standard output device.

hRunTermOutput :: Handle -> Terminal -> TermOutput -> IO () Source

Write the terminal output to the terminal or file managed by the given Handle.

termText :: String -> TermOutput Source

tiGetOutput :: String -> Capability ([Int] -> LinesAffected -> TermOutput) Source

Look up an output capability in the terminfo database.

type LinesAffected = Int Source

A parameter to specify the number of lines affected. Some capabilities (e.g., clear and dch1) use this parameter on some terminals to compute variable-length padding.

class Semigroup a => Monoid a where Source

The class of monoids (types with an associative binary operation that has an identity). Instances should satisfy the following:

Right identity

x <> mempty = x

Left identity

mempty <> x = x

Associativity

x <> (y <> z) = (x <> y) <> z (Semigroup law)

Concatenation

mconcat = foldr (<>) mempty

The method names refer to the monoid of lists under concatenation, but there are many other instances.

Some types can be viewed as a monoid in more than one way, e.g. both addition and multiplication on numbers. In such cases we often define newtypes and make those instances of Monoid, e.g. Sum and Product.

NOTE: Semigroup is a superclass of Monoid since base-4.11.0.0.

>>> "Hello world" <> mempty
"Hello world"

>>> mconcat ["Hello", " ", "Haskell", "!"]
"Hello Haskell!"

(<#>) :: Monoid m => m -> m -> m infixl 2 Source

An operator version of mappend.