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I have some data structure which are several levels deep and produce extremely long and skinny pretty printed output. It would be desirable, if only the first level (generally n levels) would prettyprint and the rest shown in the regular compact format.

I looked at the various pretty-printer on hackage, but could not find one with a functionality to pretty-print structured records up to a specified depth. Is there such a tool or how can it be constructed?

I have some data structure which are several levels deep and produce extremely long and skinny pretty printed output. It would be desirable, if only the first level (generally n levels) would prettyprint and the rest shown in the regular compact format.

I looked at the various pretty-printer on hackage, but could not find one with a functionality to pretty-print structured records up to a specified depth. Is there such a tool or how can it be constructed?

• haskell

Share Improve this question Follow asked Feb 3 at 21:56 user855443user855443 2,94855 gold badges3232 silver badges4545 bronze badges 2

• I recall an approach named "scrap your boilerplate" that could (I guess?) in principle be used to this task. It's not straightforward to learn though. I wonder if there are more modern simpler alternatives nowadays. – chi Commented Feb 3 at 23:27
• You can always hand-roll your show instance? (recursively passing down the nesting level and decreasing it by one each time) – mb21 Commented Feb 4 at 10:33

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One possible line of attack: look at prettyprinter. It renders documents to an intermediate form called SimpleDocStream. So you might try writing a renderer which either counts the stack depth or limits the indent width. Not exactly what you asked for, but something like that sounds like it would solve your problem.

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