Make postprocessing configurable #80

georgefst · 2020-09-13T21:38:57Z

Ended up writing a fix for #39, to help with a script I was writing this afternoon.

Not quite sure about the details of the API yet.

Tests expected to fail right now, though fixes should be trivial. And new tests will be added anyway.

src/Text/Pretty/Simple/Internal/Expr.hs

src/Text/Pretty/Simple/Internal/Printer.hs

Copy/paste error from 'defaultPostProcess'.

src/Text/Pretty/Simple/Internal/Printer.hs

georgefst · 2020-09-13T22:06:36Z

src/Text/Pretty/Simple/Internal/Expr.hs

  -- only thing we will be doing with it is turning it /back/ into a string
  -- at some stage, so we might as well cut out the middle man and store it
  -- directly like this.
+  | CustomExpr Style !String


This opens up a lot of flexibility. But it feels slightly ugly, since we will never actually parse a CustomExpr. We could formalise that fact with GADTs and DataKinds, but it's possibly unwarranted complexity.

cdepillabout

This looks pretty good to me!

src/Text/Pretty/Simple/Internal/Expr.hs

src/Text/Pretty/Simple/Internal/Printer.hs

Helps with defining Show instance.

Only trivial changes.

should probably be undone, effectively just stashing them

georgefst · 2024-12-08T15:35:59Z

I'm spitballing here, and I'm not sure where it falls on a spectrum anywhere from making this redundant to being completely orthogonal, but anyway, if I ever return to this, I think we should look in to integrating syb somehow to make it easy to override show output for certain types:

import Data.Data
import Data.Generics.Aliases
import Text.Pretty.Simple

gshowWith :: (Data a, Typeable b) => (b -> String) -> a -> String
gshowWith f x = gshowsWith f x ""
gshowsWith :: (Data a, Typeable b) => (b -> String) -> a -> ShowS
gshowsWith f =
    ( \t ->
        showChar '('
            . (showString . showConstr . toConstr $ t)
            . (foldr (.) id . gmapQ ((showChar ' ' .) . gshowsWith f) $ t)
            . showChar ')'
    )
        `extQ` (shows :: String -> ShowS)
        -- only here do we modify the definition of `gshows`
        `extQ` ((++) . f)

data Example = Example Int String Word | Rec () Example deriving (Data, Typeable)
example :: Example
example = Rec () $ Example 42 "Hello" 15

main :: IO ()
main =
    pPrintString $
        gshowWith
            (\(i :: Int) -> "<int: " ++ show i ++ ">")
            example

( Rec ( () )
    ( Example <int: 42> "Hello" ( 15 ) )
)

Make postprocessing configurable

69ea192