Prettyprint Show output
Output of nested data structures by Show instances is often very hard to read.
This package offers a simple function to insert line breaks and indentation into
that ouput so that the semantics are unchanged, but makes it much easier to
read.
The package does not rely on a parser for actual Haskell; instead, it merely
reacts on parentheses, commas and the like. This makes it fairly robust even in
the face of invalid Show instances, that may not produce valid Haskell code.
Examples
Artificial
Hello Foo ("(Bar", Haha) (Baz (A { foo = C, bar = D, qux = (E,"He)llo World!",G,
H,[A,B,c,d,e,Fghi]) } ) (B,C) [Baz A1 B2, (Baz A3 (B4)), (Baz A5 (B6)), (Baz
(A7) B8)]) (Foo) (Bar) (Baz (A) (B))
==>
Hello Foo ("(Bar",Haha)
(Baz (A {foo = C
,bar = D
,qux = (E
,"He)llo World!"
,G
,H
,[A,B,c,d,e,Fghi])})
(B,C)
[Baz A1 B2
,(Baz A3 (B4))
,(Baz A5 (B6))
,(Baz (A7) B8)])
(Foo)
(Bar)
(Baz (A) (B))
Inspired by a real AST
Set (fromList [(Name "A string with (parenthesis",Ann (Entry (Quality 1 1)
(Ann False) (Ann (Map [Ann (Bound (Ann (Id "lorem"))),Ann (Variable
(Ann (Id "ipsum")))])))),(Name "string",Ann (Entry (Quality 1 1) (Ann
True) (Ann (Internal (Ann (Reduce (Ann (Id "dolor")) (Ann (Id "sit")))))
))),(Name "Another } here",Ann (Entry (Quality 1 1) (Ann (Or [Ann (Not
(Ann (Is (Ann Flagged) (Ann Type) (Ann (Multi [Ann (Literal (Ann One))
]))))),Ann (Is (Ann Flagged) (Ann Type) (Ann (Multi [Ann (Literal (Ann
Three))]))),Ann (Is (Ann Flagged) (Ann Type) (Ann (Multi [Ann (Literal
(Ann Two))])))])) (Ann (Internal (Ann (Concat (Ann (Id "amet"))))))))])
==>
Set (fromList [(Name "A string with (parenthesis"
,Ann (Entry (Quality 1 1)
(Ann False)
(Ann (Map [Ann (Bound (Ann (Id "lorem")))
,Ann (Variable (Ann (Id "ipsum")))]))))
,(Name "string"
,Ann (Entry (Quality 1 1)
(Ann True)
(Ann (Internal (Ann (Reduce (Ann (Id "dolor"))
(Ann (Id "sit"))))))))
,(Name "Another } here"
,Ann (Entry (Quality 1 1)
(Ann (Or [Ann (Not (Ann (Is (Ann Flagged)
(Ann Type)
(Ann (Multi [Ann (Literal (Ann One))])))))
,Ann (Is (Ann Flagged)
(Ann Type)
(Ann (Multi [Ann (Literal (Ann Three))])))
,Ann (Is (Ann Flagged)
(Ann Type)
(Ann (Multi [Ann (Literal (Ann Two))])))]))
(Ann (Internal (Ann (Concat (Ann (Id "amet"))))))))])