Weird Aeson.Value layout

[phadej]

Given an example (based on benchmark's prettiestValue):

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Data.Aeson
import Text.PrettyPrint.Compact
import Data.Foldable (toList)

import qualified Data.HashMap.Lazy as H

prettiestJSON :: Value -> Doc ()
prettiestJSON (Bool True)  = text "true"
prettiestJSON (Bool False) = text "false"
prettiestJSON (Object o)   = encloseSep (text "{") (text "}") (text ",") (map prettyKV $ H.toList o)
  where prettyKV (k,v)     = text (show k) <> text ":" <+> prettiestJSON v
prettiestJSON (String s)   = string (show s)
prettiestJSON (Array a)    = encloseSep (text "[") (text "]") (text ",") (map prettiestJSON $ toList a)
prettiestJSON Null         = text "null"
prettiestJSON (Number n)   = text (show n)

value :: Value
value = object [ "foobar" .= three ] where
    three = object
        [ "1st" .= x
        , "2nd" .= x
        , "3rd" .= x
        ]
    x = object
        [ "kikka" .= Number 1
        , "kukka" .= Number 2
        , "pekka" .= Number 3
        , "matti" .= Number 4
        , "teppo" .= Number 5
        , "localization" .= Number 10
--        , "internationalization" .= Number 18
        ]

With some page widths, one gets weird looking results:

*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 100 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}, "3rd": {"matti": 4.0
                                          ,"pekka": 3.0
                                          ,"kukka": 2.0
                                          ,"localization": 10.0
                                          ,"kikka": 1.0
                                          ,"teppo": 5.0}, "2nd": {"matti": 4.0
                                                                 ,"pekka": 3.0
                                                                 ,"kukka": 2.0
                                                                 ,"localization": 10.0
                                                                 ,"kikka": 1.0
                                                                 ,"teppo": 5.0}}}

With slightly narrower (80) page, the layout is sensible :

{"foobar": {"1st": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"3rd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"2nd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}}}

and with wider (120) one pretty-compact does what I'd expect it to do:

{"foobar": {"1st": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"3rd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"2nd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}}}

---

I'm ok if this is a feature (I don't remember if you mention about such pathological cases in the paper), yet unfortunate one.

[jyp]

The horizontal concatenation <> does what you observe, namely tabbing the second argument against the last line of the first. This spec is necessary in certain cases. But I most certainly should add an operator which fails if its argument is multiline. On its basis we could make sure that horizontal or vertical concatenation works as you desire.

[jyp]

@phadej Please check the above commit to see if it solves the issue.

[phadej]

@jyp, it doesn't, I guess you have to actually implement

TODO: add a boolean to filter out multiline layouts.

for Doc :(

[jyp]

That's just an optimization.

I've fixed a couple of errors and it should be fine now.

Can you give it another try @phadej ?

(Branch https://github.com/jyp/prettiest/tree/single-line-cat)

[phadej]

@jyp it seems to work, but there's probably something slightly wrong:

width = 110

*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 110 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"3rd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"2nd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}}}

width = 111

Makes sense, cannot fit the two closing } for the last entry

*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 111 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"3rd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"2nd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}}}

width = 112

Same as with 110 !!!, But should be the same as above?

*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 112 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"3rd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}
           ,"2nd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}}}

width = 113

As expected

*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 113 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"3rd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"2nd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}}}

[phadej]

The 111 output is precisely the width to fit 1nd and 3rd:

*Main> putStrLn $ take 110 $ cycle "0123456789"
01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
*Main> putStrLn $ renderWith Text.PrettyPrint.Compact.defaultOptions { optsPageWidth = 111 } $ prettiestJSON value
{"foobar": {"1st": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"3rd": {"matti": 4.0, "pekka": 3.0, "kukka": 2.0, "localization": 10.0, "kikka": 1.0, "teppo": 5.0}
           ,"2nd": {"matti": 4.0
                   ,"pekka": 3.0
                   ,"kukka": 2.0
                   ,"localization": 10.0
                   ,"kikka": 1.0
                   ,"teppo": 5.0}}}

[jyp]

I fixed the bug.

I believe that the behaviour for "encloseSep" (and hcat) is that most will want, so I'm merging into the master.

[phadej]

I confirm, it seems to work properly for me. Thanks!