Moduleprettyprinter-1.7.2Haskell2010

Prettyprinter.Render.Util.StackMachine

Definitions to write renderers based on looking at a SimpleDocStream as an instruction tape for a stack machine: text is written, annotations are added (pushed) and later removed (popped).

1 type
7 values

Packageprettyprinter-1.7.2
Exports8
LanguageHaskell2010
LicenceBSD-2-Clause
SourceStackMachine.hs

Simple, pre-defined stack machines

2 declarations

These cover most basic use cases where there is not too much special logic, and all that’s important is how to render text, and how to add/remove an annotation.

valuerenderSimplyDecorated

:: Monoid out
=> (Text -> out)
Render plain Text
-> (ann -> out)
How to render an annotation
-> (ann -> out)
How to render the removed annotation
-> SimpleDocStream ann
-> out

Simplest possible stack-based renderer.

For example, here is a document annotated with (), and the behaviour is to write »>>>« at the beginning, and »<<<« at the end of the annotated region:

Example3 expressions

>>> let doc = "hello" <+> annotate () "world" <> "!">>> let sdoc = layoutPretty defaultLayoutOptions doc>>> T.putStrLn (renderSimplyDecorated id (\() -> ">>>") (\() -> "<<<") sdoc)hello >>>world<<<!

The monoid will be concatenated in a right associative fashion.

valuerenderSimplyDecoratedA

:: (Applicative f, Monoid out)
=> (Text -> f out)
Render plain Text
-> (ann -> f out)
How to render an annotation
-> (ann -> f out)
How to render the removed annotation
-> SimpleDocStream ann
-> f out

Version of renderSimplyDecoratedA that allows for Applicative effects.

General stack machine

6 declarations

These definitions allow defining a full-blown stack machine renderer, allowing for arbitrary peeking, popping and what not.

newtypenewtype StackMachine output style a

Deprecated. Writing your own stack machine is probably more efficient and customizable; also consider using »renderSimplyDecorated(A)« instead

WriterT output StateT [style] a, but with a strict Writer value.

The output type is used to append data chunks to, the style is the member of a stack of styles to model nested styles with.

Instances3Monad, Functor, Applicative

Monoid output => Monad (StackMachine output style)Defined in prettyprinter-1.7.2 · Prettyprinter.Render.Util.StackMachine
Functor (StackMachine output style)Defined in prettyprinter-1.7.2 · Prettyprinter.Render.Util.StackMachine
Monoid output => Applicative (StackMachine output style)Defined in prettyprinter-1.7.2 · Prettyprinter.Render.Util.StackMachine

valueexecStackMachine

:: [styles]
-> StackMachine output styles a
-> (output, [styles])

Run the renderer and retrieve the writing end

valuepushStyle :: Monoid output => style -> StackMachine output style ()

Add a new style to the style stack.

valueunsafePopStyle :: Monoid output => StackMachine output style style

Get the topmost style.

If the stack is empty, this raises an error.

valueunsafePeekStyle :: Monoid output => StackMachine output style style

View the topmost style, but do not modify the stack.

If the stack is empty, this raises an error.

valuewriteOutput :: output -> StackMachine output style ()

Append a value to the output end.