prettyprinter-configurable-1.30.0.0: Configurable pretty-printing
Safe HaskellSafe-Inferred
LanguageHaskell2010

Text.Fixity.Internal

Description

Precedence-general machinery for deciding whether an expression needs to be wrapped in parentheses or not. Source code has comments on the approach used and how it compares to some other known approaches.

Synopsis

Documentation

data Associativity Source #

Associativity of an operator.

Instances

Instances details
Show Associativity Source # 
Instance details

Defined in Text.Fixity.Internal

Eq Associativity Source # 
Instance details

Defined in Text.Fixity.Internal

data FixityOver prec Source #

Fixity of an operator.

We allow unary operators to have associativity, because it's useful to distinguish between an expression like -(-x) (unary minus, left-associative) and ~~b (boolean NOT, right-associative).

Associativity of unary operators also matters when pretty-printing expressions like (-x) + y, which is pretty-printed as -x + y, assuming unary minus has the same fixity as + (and both the operators are left-associative). I.e. unary minus is handled just like the binary one: (0 - x) + y is pretty-printed as 0 - x + y.

Postfix operators are handled similarly. E.g. if ! is left-associative, then (x!)! is pretty-printed as x!! and if it's right-associative -- (x!)!.

The data type is parameterized, so that the user can choose precedence to be integer/fractional, bounded/unbounded, etc (we could also allows operators to be partially or totally ordered, but at the moment prec is required to implement Ord, i.e. it has to be totally ordered). By default we go with bounded fractional precedence, see the main Text.Fixity module.

Constructors

Fixity 

Instances

Instances details
Show prec ⇒ Show (FixityOver prec) Source # 
Instance details

Defined in Text.Fixity.Internal

Methods

showsPrecIntFixityOver prec → ShowS Source #

showFixityOver prec → String Source #

showList ∷ [FixityOver prec] → ShowS Source #

Eq prec ⇒ Eq (FixityOver prec) Source # 
Instance details

Defined in Text.Fixity.Internal

Methods

(==)FixityOver prec → FixityOver prec → Bool Source #

(/=)FixityOver prec → FixityOver prec → Bool Source #

data Direction Source #

Direction in which pretty-printing goes. For example in x + y x is pretty-printed to the left of + and y is pretty-printed to the right of +.

Constructors

ToTheLeft 
ToTheRight 

Instances

Instances details
Show Direction Source # 
Instance details

Defined in Text.Fixity.Internal

Eq Direction Source # 
Instance details

Defined in Text.Fixity.Internal

data RenderContextOver prec Source #

A context that an expression is being rendered in.

Instances

Instances details
HasRenderContext RenderContext Source # 
Instance details

Defined in Text.PrettyBy.Fixity

Show prec ⇒ Show (RenderContextOver prec) Source # 
Instance details

Defined in Text.Fixity.Internal

Eq prec ⇒ Eq (RenderContextOver prec) Source # 
Instance details

Defined in Text.Fixity.Internal

encloseIn Source #

Arguments

Ord prec 
⇒ (a → a)

Enclose a value of type a in parens.

RenderContextOver prec

An outer context.

FixityOver prec

An inner fixity.

→ a 
→ a 

Enclose an a (using the provided function) if required or leave it as is. The need for enclosing is determined from an outer RenderContext and the inner fixity.