Show package:rebase

Conversion of values to readable Strings. Derived instances of Show have the following properties, which are compatible with derived instances of Read:

• The result of show is a syntactically correct Haskell expression containing only constants, given the fixity declarations in force at the point where the type is declared. It contains only the constructor names defined in the data type, parentheses, and spaces. When labelled constructor fields are used, braces, commas, field names, and equal signs are also used.
• If the constructor is defined to be an infix operator, then showsPrec will produce infix applications of the constructor.
• the representation will be enclosed in parentheses if the precedence of the top-level constructor in x is less than d (associativity is ignored). Thus, if d is 0 then the result is never surrounded in parentheses; if d is 11 it is always surrounded in parentheses, unless it is an atomic expression.
• If the constructor is defined using record syntax, then show will produce the record-syntax form, with the fields given in the same order as the original declaration.

For example, given the declarations

infixr 5 :^:
data Tree a =  Leaf a  |  Tree a :^: Tree a

the derived instance of Show is equivalent to

instance (Show a) => Show (Tree a) where

showsPrec d (Leaf m) = showParen (d > app_prec) $
showString "Leaf " . showsPrec (app_prec+1) m
where app_prec = 10

showsPrec d (u :^: v) = showParen (d > up_prec) $
showsPrec (up_prec+1) u .
showString " :^: "      .
showsPrec (up_prec+1) v
where up_prec = 5

Note that right-associativity of :^: is ignored. For example,

• show (Leaf 1 :^: Leaf 2 :^: Leaf 3) produces the string "Leaf 1 :^: (Leaf 2 :^: Leaf 3)".

A specialised variant of showsPrec, using precedence context zero, and returning an ordinary String.

The shows functions return a function that prepends the output String to an existing String. This allows constant-time concatenation of results using function composition.

Show non-negative Integral numbers in base 2.

utility function converting a Char to a show function that simply prepends the character unchanged.

Gets the string for a constructor

Show a signed RealFloat value using scientific (exponential) notation (e.g. 2.45e2, 1.5e-3). In the call showEFloat digs val, if digs is Nothing, the value is shown to full precision; if digs is Just d, then at most d digits after the decimal point are shown.

Show a signed RealFloat value using standard decimal notation (e.g. 245000, 0.0015). In the call showFFloat digs val, if digs is Nothing, the value is shown to full precision; if digs is Just d, then at most d digits after the decimal point are shown.

Show a signed RealFloat value using standard decimal notation (e.g. 245000, 0.0015). This behaves as showFFloat, except that a decimal point is always guaranteed, even if not needed.

Show a signed RealFloat value to full precision using standard decimal notation for arguments whose absolute value lies between 0.1 and 9,999,999, and scientific notation otherwise.

Show a signed RealFloat value using standard decimal notation for arguments whose absolute value lies between 0.1 and 9,999,999, and scientific notation otherwise. In the call showGFloat digs val, if digs is Nothing, the value is shown to full precision; if digs is Just d, then at most d digits after the decimal point are shown.

Show a signed RealFloat value using standard decimal notation for arguments whose absolute value lies between 0.1 and 9,999,999, and scientific notation otherwise. This behaves as showFFloat, except that a decimal point is always guaranteed, even if not needed.

Show in ISO 8601 format (yyyy-mm-dd)

Show a floating-point value in the hexadecimal format, similar to the %a specifier in C's printf.

>>> showHFloat (212.21 :: Double) ""
"0x1.a86b851eb851fp7"

>>> showHFloat (-12.76 :: Float) ""
"-0x1.9851ecp3"

>>> showHFloat (-0 :: Double) ""
"-0x0p+0"

Show non-negative Integral numbers in base 16.

Show non-negative Integral numbers in base 10.

Shows a non-negative Integral number using the base specified by the first argument, and the character representation specified by the second.

The method showList is provided to allow the programmer to give a specialised way of showing lists of values. For example, this is used by the predefined Show instance of the Char type, where values of type String should be shown in double quotes, rather than between square brackets.

Convert a character to a string using only printable characters, using Haskell source-language escape conventions. For example:

showLitChar '\n' s  =  "\\n" ++ s

Show non-negative Integral numbers in base 8.

utility function that surrounds the inner show function with parentheses when the Bool parameter is True.

Converts a possibly-negative Real value to a string.

utility function converting a String to a show function that simply prepends the string unchanged.