Hello everyone. Does any of you know where I can find a decent tutorial for the OCaml Format module ? I cannot figure out how to use it, and the few things I have found are the documentation and the official tutorial, which are explicit but not clear at all. I have spent the last 30 minutes trying t…

I would recommend reading this blog post: https://cedeela.fr/format-all-the-data-structures.html For understanding boxes, see https://ocaml.org/learn/tutorials/format.html

I’ll have a look at it. Thanks !

If that’s an option for you, I’d suggest using easy-format . There’s a complete example here with various ways to format the same thing.

I vividly remember how strange it looked the first time I tried using it. Other people recommended some resources to understand how to used it and how the boxing model works. I strongly recommend using the fmt library that abstracts a lot of complexity of the Format module.

I would actually recommend against easy-format. Fmt gives you a better API, but without adding layers upon layers of indirection and a direct compatibility with all the printers out there. Format has a terrible API, but you don’t have to use it nowadays, Fmt and CCFormat are 100% compatible, includ…

I wonder what you use Format and descendants for? I made easy-format around 2010 so I could pretty-print json and code in general, like a programmer would. Printing things like this using just Format was incredibly tricky: { "field": { "number": 123, "text": "aaaaaaaaaaaaaaaaaaaaaaaaaaaa…

[image] mjambon: This requires a box with negative indentation for the } to be aligned with "field": { rather than with "text": . No it doesn’t, Just close the box before closing the parens: # Fmt.pr {|@[<v2>"%s": {@ %a@]@ }|} "foo" Fmt.(list ~sep:cut string) [ "aaa"; "bbb"…

Not a tutorial, but you might find it helpful to see some examples of Format usage. Here’s a pretty-printer for a small subset of XML: https://gist.github.com/keleshev/5af7502e6810b8986d9f5332e7e8a795 xml.ml #! /usr/bin/env ocaml let fprintf = Format.fprintf type t = | Tag of {name: st…

Maybe these examples should be added to the manual of Format?

Format module from the Standard Library

Learning

jhaberku July 10, 2018, 2:34pm 5

Check out this paper, whose purpose is to explain and document the module.

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Format module from the Standard Library

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