[Haskell-cafe] Prettyprinting infix expressions with HughesPJ
alfonso.acosta at gmail.com
Tue Apr 10 03:20:52 EDT 2007
I have to prettyprint infix expressions writing the least possible
parenthesis (taking in account precedence and associativity). A
simplified expression type could be:
data Expr = Val String |
-- Binary operators (using infix constructors)
Expr :+: Expr | Expr :-: Expr |
Expr :*: Expr | Expr :/: Expr |
Expr :^: Expr |
-- Unary operators
I'm using HughesPJ for the rest of my AST (not just expressions) but
the library doesn't provide any mechanism to help coding this kind of
prettyprinter so I decided to simply use the standard showsPrec and
then feed HughesPJ with the obtained text .
showsPrec helps to take advantage of the precedence information.
However, I don't find a way to remove parenthesis according to
I'm sure this kind of prettyprinting has been already done zillions of
times in Haskell. Any suggestions?
Thanks in advance,
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