Safe Haskell | None |
---|---|
Language | Haskell2010 |
This module exports the ShowFunction
typeclass,
its instances and related functions.
Using this module, it is possible to implement a Show instance for functions:
import Test.LeanCheck.ShowFunction instance (Show a, Listable a, ShowFunction b) => Show (a->b) where show = showFunction 8
This shows functions as a case pattern with up to 8 cases.
The module
Test.LeanCheck.Function.Show
(Show
)
exports an instance like the one above.
- showFunction :: ShowFunction a => Int -> a -> String
- showFunctionLine :: ShowFunction a => Int -> a -> String
- type Binding = ([String], Maybe String)
- bindings :: ShowFunction a => a -> [Binding]
- class ShowFunction a where
- tBindingsShow :: Show a => a -> [[Binding]]
- class Listable a
Documentation
showFunction :: ShowFunction a => Int -> a -> String Source #
Given a number of patterns to show, shows a ShowFunction
value.
showFunction undefined True == "True" showFunction 3 (id::Int) == "\\x -> case x of\n\ \ 0 -> 0\n\ \ 1 -> 1\n\ \ -1 -> -1\n\ \ ...\n" showFunction 4 (&&) == "\\x y -> case (x,y) of\n\ \ (False,False) -> False\n\ \ (False,True) -> False\n\ \ (True,False) -> False\n\ \ (True,True) -> True\n"
This can be used as an implementation of show for functions:
instance (Show a, Listable a, ShowFunction b) => Show (a->b) where show = showFunction 8
showFunctionLine :: ShowFunction a => Int -> a -> String Source #
Same as showFunction, but has no line breaks.
showFunction 2 (id::Int) == "\\x -> case x of 0 -> 0; 1 -> 1; ..."
bindings :: ShowFunction a => a -> [Binding] Source #
Given a ShowFunction
value, return a list of bindings
for printing. Examples:
bindings True == [([],True)] bindings (id::Int) == [(["0"],"0"), (["1"],"1"), (["-1"],"-1"), ... bindings (&&) == [ (["False","False"], "False") , (["False","True"], "False") , (["True","False"], "False") , (["True","True"], "True") ]
class ShowFunction a where Source #
ShowFunction
values are those for which
we can return a list of functional bindings.
As a user, you probably want showFunction
and showFunctionLine
.
Non functional instances should be defined by:
instance ShowFunction Ty where tBindings = tBindingsShow
ShowFunction Bool Source # | |
ShowFunction Char Source # | |
ShowFunction Int Source # | |
ShowFunction () Source # | |
Show a => ShowFunction [a] Source # | |
Show a => ShowFunction (Maybe a) Source # | |
(Show a, Listable a, ShowFunction b) => ShowFunction (a -> b) Source # | |
(Show a, Show b) => ShowFunction (a, b) Source # | |
(Show a, Show b, Show c) => ShowFunction (a, b, c) Source # | |
(Show a, Show b, Show c, Show d) => ShowFunction (a, b, c, d) Source # | |
(Show a, Show b, Show c, Show d, Show e) => ShowFunction (a, b, c, d, e) Source # | |
(Show a, Show b, Show c, Show d, Show e, Show f) => ShowFunction (a, b, c, d, e, f) Source # | |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g) => ShowFunction (a, b, c, d, e, f, g) Source # | |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h) => ShowFunction (a, b, c, d, e, f, g, h) Source # | |
tBindingsShow :: Show a => a -> [[Binding]] Source #
A default implementation of tBindings for already Show
-able types.
Re-exports
A type is Listable
when there exists a function that
is able to list (ideally all of) its values.
Ideally, instances should be defined by a tiers
function that
returns a (potentially infinite) list of finite sub-lists (tiers):
the first sub-list contains elements of size 0,
the second sub-list contains elements of size 1
and so on.
Size here is defined by the implementor of the type-class instance.
For algebraic data types, the general form for tiers
is
tiers = cons<N> ConstructorA \/ cons<N> ConstructorB \/ ... \/ cons<N> ConstructorZ
where N
is the number of arguments of each constructor A...Z
.
Instances can be alternatively defined by list
.
In this case, each sub-list in tiers
is a singleton list
(each succeeding element of list
has +1 size).
The function deriveListable
from Test.LeanCheck.Derive
can automatically derive instances of this typeclass.
A Listable
instance for functions is also available but is not exported by
default. Import Test.LeanCheck.Function if you need to test higher-order
properties.