haskell-src-exts-1.8.1: Manipulating Haskell source: abstract syntax, lexer, parser, and pretty-printer

MaintainerNiklas Broberg, d00nibro@chalmers.se




Fixity information to give the parser so that infix operators can be parsed properly.


Fixity representation

data Fixity Source

Operator fixities are represented by their associativity (left, right or none) and their precedence (0-9).


Fixity Assoc Int Op 


The following three functions all create lists of fixities from textual representations of operators. The intended usage is e.g.

 fixs = infixr_ 0  ["$","$!","`seq`"]

Note that the operators are expected as you would write them infix, i.e. with ` characters surrounding varid operators, and varsym operators written as is.

Collections of fixities

preludeFixities :: [Fixity]Source

All fixities defined in the Prelude.

baseFixities :: [Fixity]Source

All fixities defined in the base package.

Note that the +++ operator appears in both Control.Arrows and Text.ParserCombinators.ReadP. The listed precedence for +++ in this list is that of Control.Arrows.

Applying fixities to an AST

class AppFixity ast whereSource

All AST elements that may include expressions which in turn may need fixity tweaking will be instances of this class.




:: Monad m 
=> [Fixity]

The fixities to account for.

-> ast SrcSpanInfo

The element to tweak.

-> m (ast SrcSpanInfo)

The same element, but with operator expressions updated, or a failure.

Tweak any expressions in the element to account for the fixities given. Assumes that all operator expressions are fully left associative chains to begin with.