Control.PatternArrows

Arrows for Pretty Printing

Documentation

newtype Pattern u a b

A first-order pattern match

A pattern is a Kleisli arrow for the StateT Maybe monad. That is, patterns can fail, and can carry user-defined state.

Constructors

Pattern

Fields

runPattern :: Kleisli (StateT u Maybe) a b

Instances

Arrow (Pattern u)

ArrowZero (Pattern u)

ArrowPlus (Pattern u)

Category (Pattern u)

Functor (Pattern u a)

pattern :: Pattern u a b -> u -> a -> Maybe b

Run a pattern with an input and initial user state

Returns Nothing if the pattern fails to match

mkPattern :: (a -> Maybe b) -> Pattern u a b

Construct a pattern from a function

mkPattern' :: (a -> StateT u Maybe b) -> Pattern u a b

Construct a pattern from a stateful function

chainl :: Pattern u a (a, a) -> (r -> r -> r) -> Pattern u a r -> Pattern u a r

Construct a pattern which recursively matches on the left-hand-side

chainr :: Pattern u a (a, a) -> (r -> r -> r) -> Pattern u a r -> Pattern u a r

Construct a pattern which recursively matches on the right-hand side

wrap :: Pattern u a (s, a) -> (s -> r -> r) -> Pattern u a r -> Pattern u a r

Construct a pattern which recursively matches on one-side of a tuple

split :: Pattern u a (s, t) -> (s -> t -> r) -> Pattern u a r

Construct a pattern which matches a part of a tuple

data OperatorTable u a r

A table of operators

Constructors

OperatorTable

Fields

runOperatorTable :: [[Operator u a r]]

data Operator u a r where

An operator:

AssocL

A left-associative operator

AssocR

A right-associative operator

Wrap

A prefix-like or postfix-like operator

Split

A prefix-like or postfix-like operator which does not recurse into its operand

Constructors

AssocL :: Pattern u a (a, a) -> (r -> r -> r) -> Operator u a r

AssocR :: Pattern u a (a, a) -> (r -> r -> r) -> Operator u a r

Wrap :: Pattern u a (s, a) -> (s -> r -> r) -> Operator u a r

Split :: Pattern u a (s, t) -> (s -> t -> r) -> Operator u a r

buildPrettyPrinter :: OperatorTable u a r -> Pattern u a r -> Pattern u a r

Build a pretty printer from an operator table and an indecomposable pattern