Module Prelude.PreludeText

Classes and Instances to convert values to Strings (Show.show) and Strings to values ("read").

There are a few differences to Haskell, notably

"Read" cannot be derived and supports only simple types

Imports

import Java.Lang as Lang
import Prelude.Maybe as Maybe
import Prelude.PreludeBase as PreludeBase
import Prelude.PreludeList as PreludeList
import Prelude.PreludeMonad as PreludeMonad
import Java.util.Regex as Regexp
import Control.Semigroupoid as Semigroupoid

Table of Content

Definitions

type ReadS a = StringJ Char → [(a, StringJ Char)]

type ShowS = StringJ Char → StringJ Char

class Read a

class Show show

joined ∷ String → [String] → String

packed ∷ [Char] → String

shows ∷ Show a ⇒ a → String → String

showChar ∷ Char → String → String

showString ∷ String → String → String

showParen ∷ Bool → (String → String) → String → String

lines ∷ String → [String]

lineSeparator ∷ String

unlines ∷ [String] → String

chomp ∷ String → String

splittedWords ∷ String → [String]

words ∷ String → [String]

unwords ∷ [String] → String
Instances

instance Read Int

instance Show ()

instance (Show a, Show b) ⇒ Show (a, b)

instance (Show a, Show b, Show c) ⇒ Show (a, b, c)

instance Show Bool

instance Show Byte

instance Show Char

instance Show Double

instance (Show a, Show b) ⇒ Show (a | b)

instance Show Float

instance Show Int

instance Show Integer

instance Show Long

instance Show a ⇒ Show (Maybe a)

instance Show Ordering

instance Show Regex

instance Show Short

instance Show String

instance Show Throwable

instance Show a ⇒ Show [a]
Functions and Values by Type

Definitions

type ShowS = StringJ Char → StringJ Char

Haskell compatibility

type ReadS a = StringJ Char → [(a, StringJ Char)]

Haskell compatibility

class Show show

Class Show provides operations to convert values to Strings.

This class can be derived for all algebraic data types whose constituents are themselves instances of Show.

Known Instances

Bool, (), (,), (,,), Int, Char, Lang.Byte, Either, Double, Float, StringJ, Ordering, Long, Integer, Maybe, Lang.Short, Regex, [], Throwable

Member Functions

display ∷ Show show ⇒ show → String

Show.display computes an alternate string representation of a value and is used in the Char and String instances of Show to produce an unquoted string.

The default implementation is to do the same as Show.show.

show ∷ Show show ⇒ show → String

Computes the string representation of a value.

Every instance must implement Show.show.

showChars ∷ Show show ⇒ show → [Char]

Show.showChars addresses the problem of Show.showing infinite values. Because Show.show has type String and String is atomic, this would try to create a string with infinite length, and hence is doomed to fail.

The default definition is

 showChars = String.toList . show

This is ok for all finite values. But instances for recursive types should implement it in a way that produces a lazy list of characters.

Here is an example for the list instance:

 showChars [] = ['[', ']']
 showChars xs = '[' : ( tail [ c | x <- xs, c <- ',' : showChars x ] ++ [']'] )

showList ∷ Show show ⇒ [show] → String → String

Haskell compatibility

showsPrec ∷ Show show ⇒ Int → show → String → String

Haskell compatibility

showsub ∷ Show show ⇒ show → String

Show.showsub is used for Show.showing elements of a value of an algebraic data type in derived instances of Show.

The generated code in derived instances for types that are not enumerations is

 showsub x = "(" ++ show x ++ ")"

so that values are enclosed in parentheses. Certain types like records, lists, tuples and many primitive types do not need extra parentheses, and thus Show.showsub is the same as Show.show, which is also the default implementation.

In short,

in derived instances, Show.showsub will do the right thing.
in all other instances, Show.showsub will do the same as Show.show if not implemented differently.

Example:

 derive Show ( Maybe b)

implements the following:

 show Nothing = "Nothing"
 show (Just x) = "Just " ++ x.showsub
 showsub x = "(" ++ show x ++ ")"

so that

 show (Just (Just 42)) == "Just (Just 42)"

joined ∷ String → [String] → String

joined sep xs concatenates all strings in /xs/, and inserts /sep/ between any two elements of /xs/.

If /xs/ is empty, the result is an empty string. If /sep/ is an empty string, then the result is just the concatenation of the strings in /xs/.

Example:

 joined ", " ["aaa", "bbb", "ccc"] == "aaa, bbb, ccc"

packed ∷ [Char] → String

convert a list of characters to a string

 packed ['a', 'b', 'c' ] == "abc"

shows ∷ Show a ⇒ a → String → String

Haskell compatibility

showChar ∷ Char → String → String

Haskell compatibility

showString ∷ String → String → String

Haskell compatibility

showParen ∷ Bool → (String → String) → String → String

Haskell compatibility

class Read a

Preliminary substitute for Read

Known Instances

Int

Member Functions

read ∷ Read a ⇒ String → a

lines ∷ String → [String]

splits a String on end-of-line and returns a list of Strings

The last line may or may not be terminated by newline.

End-of-line is signaled by a number of carriage returns followed by a new line.

This should work for UNIX and Windows.

lineSeparator ∷ String

The line separator suitable for the platform the program is running on.

unlines ∷ [String] → String

unlines is an inverse operation to lines.

It joins lines, after appending a terminating newline to each.

chomp ∷ String → String

strip trailing spaces, tabs, newline and carriage return characters from a string

splittedWords ∷ String → [String]

splits a String on non empty sequences of spaces and returns a list of Strings

Since this uses java.util.Regex.split the result will start with an empty string if the argument starts with spaces. This is a difference to words, which, according to the Haskell standard, does not include the empty string.

words ∷ String → [String]

splits a String on non empty sequences of spaces and returns a list of non-empty Strings

unwords ∷ [String] → String

unwords is an inverse operation to words.

It joins words with separating spaces.

Instances

instance Read Int

Member Functions

read ∷ String → Int

instance Show ()

Member Functions

display ∷ () → String: inherited from Show.display
show ∷ () → String: Function generated for derived instance.
showChars ∷ () → [Char]: inherited from Show.showChars
showList ∷ [()] → String → String: inherited from Show.showList
showsPrec ∷ Int → () → String → String: inherited from Show.showsPrec
showsub ∷ () → String: Function generated for derived instance.

instance (Show a, Show b) ⇒ Show (a, b)

Member Functions

display ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → String: inherited from Show.display
show ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → String: Function generated for derived instance.
showChars ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → [Char]: inherited from Show.showChars
showList ∷ (Show 𝖇, Show 𝖆) ⇒ [(𝖇, 𝖆)] → String → String: inherited from Show.showList
showsPrec ∷ (Show 𝖇, Show 𝖆) ⇒ Int → (𝖇, 𝖆) → String → String: inherited from Show.showsPrec
showsub ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → String: inherited from Show.showsub

instance (Show a, Show b, Show c) ⇒ Show (a, b, c)

Member Functions

display ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → String: inherited from Show.display
show ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → String: Function generated for derived instance.
showChars ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → [Char]: inherited from Show.showChars
showList ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ [(𝖇, 𝖈, 𝖆)] → String → String: inherited from Show.showList
showsPrec ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ Int → (𝖇, 𝖈, 𝖆) → String → String: inherited from Show.showsPrec
showsub ∷ (Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → String: inherited from Show.showsub

instance Show Bool

Member Functions

display ∷ Bool → String: inherited from Show.display
show ∷ Bool → String
showChars ∷ Bool → [Char]: inherited from Show.showChars
showList ∷ [Bool] → String → String: inherited from Show.showList
showsPrec ∷ Int → Bool → String → String: inherited from Show.showsPrec
showsub ∷ Bool → String: inherited from Show.showsub

instance Show Byte

Member Functions

display ∷ Byte → String: inherited from Show.display
show ∷ Byte → String
showChars ∷ Byte → [Char]: inherited from Show.showChars
showList ∷ [Byte] → String → String: inherited from Show.showList
showsPrec ∷ Int → Byte → String → String: inherited from Show.showsPrec
showsub ∷ Byte → String: inherited from Show.showsub

instance Show Char

Member Functions

display ∷ Char → String

construct a string that consists of just this character

show ∷ Char → String
pure native frege.runtime.Runtime.quoteChr

reconstructs a Java char literal from a character, i.e.

 show 'a' = "'a'"

showChars ∷ Char → [Char]

inherited from Show.showChars

showList ∷ [Char] → String → String

the string created from the characters

showsPrec ∷ Int → Char → String → String

inherited from Show.showsPrec

showsub ∷ Char → String

inherited from Show.showsub

instance Show Double

Member Functions

display ∷ Double → String: inherited from Show.display
show ∷ Double → String
pure native java.lang.Double.toString
showChars ∷ Double → [Char]: inherited from Show.showChars
showList ∷ [Double] → String → String: inherited from Show.showList
showsPrec ∷ Int → Double → String → String: inherited from Show.showsPrec
showsub ∷ Double → String: inherited from Show.showsub

instance (Show a, Show b) ⇒ Show (a | b)

Member Functions

display ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → String: inherited from Show.display
show ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → String: Function generated for derived instance.
showChars ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → [Char]: inherited from Show.showChars
showList ∷ (Show 𝖇, Show 𝖆) ⇒ [(𝖇 | 𝖆)] → String → String: inherited from Show.showList
showsPrec ∷ (Show 𝖇, Show 𝖆) ⇒ Int → (𝖇 | 𝖆) → String → String: inherited from Show.showsPrec
showsub ∷ (Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → String: Function generated for derived instance.

instance Show Float

Member Functions

display ∷ Float → String: inherited from Show.display
show ∷ Float → String
pure native java.lang.Float.toString
showChars ∷ Float → [Char]: inherited from Show.showChars
showList ∷ [Float] → String → String: inherited from Show.showList
showsPrec ∷ Int → Float → String → String: inherited from Show.showsPrec
showsub ∷ Float → String: inherited from Show.showsub

instance Show Int

Member Functions

display ∷ Int → String: inherited from Show.display
show ∷ Int → String
pure native java.lang.String.valueOf: the String representation of the Int argument, uses java.lang.String.valueOf
showChars ∷ Int → [Char]: inherited from Show.showChars
showList ∷ [Int] → String → String: inherited from Show.showList
showsPrec ∷ Int → Int → String → String: inherited from Show.showsPrec
showsub ∷ Int → String: inherited from Show.showsub

instance Show Integer

Member Functions

display ∷ Integer → String: inherited from Show.display
show ∷ Integer → String
pure native toString: the String representation of the Integer argument, uses BigInteger.toString
showChars ∷ Integer → [Char]: inherited from Show.showChars
showList ∷ [Integer] → String → String: inherited from Show.showList
showsPrec ∷ Int → Integer → String → String: inherited from Show.showsPrec
showsub ∷ Integer → String: inherited from Show.showsub

instance Show Long

Member Functions

display ∷ Long → String: inherited from Show.display
show ∷ Long → String
pure native java.lang.Long.toString: the String representation of the Long argument, uses java.lang.Long.toString
showChars ∷ Long → [Char]: inherited from Show.showChars
showList ∷ [Long] → String → String: inherited from Show.showList
showsPrec ∷ Int → Long → String → String: inherited from Show.showsPrec
showsub ∷ Long → String: inherited from Show.showsub

instance Show a ⇒ Show (Maybe a)

Member Functions

display ∷ Show 𝖆 ⇒ Maybe 𝖆 → String: inherited from Show.display
show ∷ Show 𝖆 ⇒ Maybe 𝖆 → String: Function generated for derived instance.
showChars ∷ Show 𝖆 ⇒ Maybe 𝖆 → [Char]: inherited from Show.showChars
showList ∷ Show 𝖆 ⇒ [Maybe 𝖆] → String → String: inherited from Show.showList
showsPrec ∷ Show 𝖆 ⇒ Int → Maybe 𝖆 → String → String: inherited from Show.showsPrec
showsub ∷ Show 𝖆 ⇒ Maybe 𝖆 → String: Function generated for derived instance.

instance Show Ordering

Member Functions

display ∷ Ordering → String: inherited from Show.display
show ∷ Ordering → String: Function generated for derived instance.
showChars ∷ Ordering → [Char]: inherited from Show.showChars
showList ∷ [Ordering] → String → String: inherited from Show.showList
showsPrec ∷ Int → Ordering → String → String: inherited from Show.showsPrec
showsub ∷ Ordering → String: Function generated for derived instance.

instance Show Regex

Member Functions

display ∷ Regex → String: inherited from Show.display
show ∷ Regex → String
showChars ∷ Regex → [Char]: inherited from Show.showChars
showList ∷ [Regex] → String → String: inherited from Show.showList
showsPrec ∷ Int → Regex → String → String: inherited from Show.showsPrec
showsub ∷ Regex → String: inherited from Show.showsub

instance Show Short

Member Functions

display ∷ Short → String: inherited from Show.display
show ∷ Short → String
showChars ∷ Short → [Char]: inherited from Show.showChars
showList ∷ [Short] → String → String: inherited from Show.showList
showsPrec ∷ Int → Short → String → String: inherited from Show.showsPrec
showsub ∷ Short → String: inherited from Show.showsub

instance Show String

Member Functions

display ∷ String → String

show ∷ String → String
pure native frege.runtime.Runtime.quoteStr

reconstructs a Java string literal from a string, i.e.

 show "abc" = "\"abc\""

showChars ∷ String → [Char]

inherited from Show.showChars

showList ∷ [String] → String → String

inherited from Show.showList

showsPrec ∷ Int → String → String → String

inherited from Show.showsPrec

showsub ∷ String → String

inherited from Show.showsub

instance Show Throwable

Member Functions

display ∷ Throwable → String

inherited from Show.display

show ∷ Throwable → String

creates a string representation of a Java exception, consisting of the class name and the message, like

 "java.lang.ArithmeticException: division by zero"

showChars ∷ Throwable → [Char]

inherited from Show.showChars

showList ∷ [Throwable] → String → String

inherited from Show.showList

showsPrec ∷ Int → Throwable → String → String

inherited from Show.showsPrec

showsub ∷ Throwable → String

inherited from Show.showsub

instance Show a ⇒ Show [a]

Member Functions

display ∷ Show 𝖆 ⇒ [𝖆] → String: inherited from Show.display
show ∷ Show 𝖆 ⇒ [𝖆] → String
showChars ∷ Show 𝖆 ⇒ [𝖆] → [Char]
showList ∷ Show 𝖆 ⇒ [[𝖆]] → String → String: inherited from Show.showList
showsPrec ∷ Show 𝖆 ⇒ Int → [𝖆] → String → String: inherited from Show.showsPrec
showsub ∷ Show 𝖆 ⇒ [𝖆] → String: inherited from Show.showsub

Functions and Values by Type

String → String → String: showString
String → [String] → String: joined
String → String: chomp, Show_String.showsub, Show_String.display, Show_String.show
String → [String]: lines, splittedWords, words
String → [Char]: Show_String.showChars
String → Int: Read_Int.read
[String] → String → String: Show_String.showList
[String] → String: unlines, unwords
[Byte] → String → String: Show_Byte.showList
[Short] → String → String: Show_Short.showList
[Regex] → String → String: Show_Regex.showList
[()] → String → String: Show_().showList
[Bool] → String → String: Show_Bool.showList
[Char] → String → String: Show_Char.showList
[Char] → String: packed
[Double] → String → String: Show_Double.showList
[Float] → String → String: Show_Float.showList
[Int] → String → String: Show_Int.showList
[Integer] → String → String: Show_Integer.showList
[Long] → String → String: Show_Long.showList
[Ordering] → String → String: Show_Ordering.showList
[Throwable] → String → String: Show_Throwable.showList
Byte → String: Show_Byte.showsub, Show_Byte.display, Show_Byte.show
Byte → [Char]: Show_Byte.showChars
Short → String: Show_Short.showsub, Show_Short.display, Show_Short.show
Short → [Char]: Show_Short.showChars
Regex → String: Show_Regex.showsub, Show_Regex.display, Show_Regex.show
Regex → [Char]: Show_Regex.showChars
() → String: Show_().showsub, Show_().display, Show_().show
() → [Char]: Show_().showChars
Bool → (String → String) → String → String: showParen
Bool → String: Show_Bool.showsub, Show_Bool.display, Show_Bool.show
Bool → [Char]: Show_Bool.showChars
Char → String → String: showChar
Char → String: Show_Char.showsub, Show_Char.display, Show_Char.show
Char → [Char]: Show_Char.showChars
Double → String: Show_Double.showsub, Show_Double.display, Show_Double.show
Double → [Char]: Show_Double.showChars
Float → String: Show_Float.showsub, Show_Float.display, Show_Float.show
Float → [Char]: Show_Float.showChars
Int → String → String → String: Show_String.showsPrec
Int → Byte → String → String: Show_Byte.showsPrec
Int → Short → String → String: Show_Short.showsPrec
Int → Regex → String → String: Show_Regex.showsPrec
Int → () → String → String: Show_().showsPrec
Int → Bool → String → String: Show_Bool.showsPrec
Int → Char → String → String: Show_Char.showsPrec
Int → Double → String → String: Show_Double.showsPrec
Int → Float → String → String: Show_Float.showsPrec
Int → Int → String → String: Show_Int.showsPrec
Int → Integer → String → String: Show_Integer.showsPrec
Int → Long → String → String: Show_Long.showsPrec
Int → Ordering → String → String: Show_Ordering.showsPrec
Int → Throwable → String → String: Show_Throwable.showsPrec
Int → String: Show_Int.showsub, Show_Int.display, Show_Int.show
Int → [Char]: Show_Int.showChars
Integer → String: Show_Integer.showsub, Show_Integer.display, Show_Integer.show
Integer → [Char]: Show_Integer.showChars
Long → String: Show_Long.showsub, Show_Long.display, Show_Long.show
Long → [Char]: Show_Long.showChars
Ordering → String: Show_Ordering.showsub, Show_Ordering.display, Show_Ordering.show
Ordering → [Char]: Show_Ordering.showChars
Throwable → String: Show_Throwable.showsub, Show_Throwable.display, Show_Throwable.show
Throwable → [Char]: Show_Throwable.showChars
String: lineSeparator
Read a ⇒ String → a: Read.read
Show a ⇒ a → String → String: shows
Show show ⇒ [show] → String → String: Show.showList
Show show ⇒ Int → show → String → String: Show.showsPrec
Show show ⇒ show → String: Show.showsub, Show.display, Show.show
Show show ⇒ show → [Char]: Show.showChars
Show 𝖆 ⇒ Maybe 𝖆 → String: Show_Maybe.showsub, Show_Maybe.display, Show_Maybe.show
Show 𝖆 ⇒ Maybe 𝖆 → [Char]: Show_Maybe.showChars
Show 𝖆 ⇒ [Maybe 𝖆] → String → String: Show_Maybe.showList
Show 𝖆 ⇒ [[𝖆]] → String → String: Show_[].showList
Show 𝖆 ⇒ [𝖆] → String: Show_[].showsub, Show_[].display, Show_[].show
Show 𝖆 ⇒ [𝖆] → [Char]: Show_[].showChars
Show 𝖆 ⇒ Int → Maybe 𝖆 → String → String: Show_Maybe.showsPrec
Show 𝖆 ⇒ Int → [𝖆] → String → String: Show_[].showsPrec
(Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → String: Show_(,).showsub, Show_(,).display, Show_(,).show
(Show 𝖇, Show 𝖆) ⇒ (𝖇, 𝖆) → [Char]: Show_(,).showChars
(Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → String: Show_Either.showsub, Show_Either.display, Show_Either.show
(Show 𝖇, Show 𝖆) ⇒ (𝖇 | 𝖆) → [Char]: Show_Either.showChars
(Show 𝖇, Show 𝖆) ⇒ [(𝖇, 𝖆)] → String → String: Show_(,).showList
(Show 𝖇, Show 𝖆) ⇒ [(𝖇 | 𝖆)] → String → String: Show_Either.showList
(Show 𝖇, Show 𝖆) ⇒ Int → (𝖇, 𝖆) → String → String: Show_(,).showsPrec
(Show 𝖇, Show 𝖆) ⇒ Int → (𝖇 | 𝖆) → String → String: Show_Either.showsPrec
(Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → String: Show_(,,).showsub, Show_(,,).display, Show_(,,).show
(Show 𝖇, Show 𝖈, Show 𝖆) ⇒ (𝖇, 𝖈, 𝖆) → [Char]: Show_(,,).showChars
(Show 𝖇, Show 𝖈, Show 𝖆) ⇒ [(𝖇, 𝖈, 𝖆)] → String → String: Show_(,,).showList
(Show 𝖇, Show 𝖈, Show 𝖆) ⇒ Int → (𝖇, 𝖈, 𝖆) → String → String: Show_(,,).showsPrec