Show package:relude

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)".
Generalized version of show. Unlike show this function is polymorphic in its result type. This makes it more convenient to work with data types like Text or ByteString. However, if you pass the result of show to a function that expects polymorphic argument, this can break type inference, so use -XTypeApplications to specify the textual type explicitly.
>>> show (42 :: Int)
"42"

>>> show (42 :: Double)
"42.0"

>>> print (show @Text True)
"True"
Get a string representation of the current execution stack state.
Warning: traceShow remains in code
Warning: traceShowId remains in code
Warning: traceShowM remains in code
Warning: 'traceShowWith remains in code