Re: [Haskell-cafe] Serialize to Haskell

This seems to be what I need! I'll give a look. On Sat, Aug 8, 2015 at 1:24 AM, Matthew Pickering < matthewtpickering@gmail.com> wrote:

Alan Zimmerman and myself have written a library which aims to make these sorts of transformations easy. We are still in the early stages but depending on what exactly you want to do then it might be suitable for your purposes. Looking now on hackage the documentation isn't very good so it might not be obvious how you're meant to use it.

https://hackage.haskell.org/package/ghc-exactprint

The basic idea is, use one of the parsers from the Parsers module, do a (generic) transformation on the resulting ast, then call `exactPrintWithAnns` on the AST and the resulting annotations. For simple transformations (moving, deletion, renaming) it is sufficient to not modify the annotations. When doing insertions/replacements, you will probably have to modify the annotations in some way to get a sensible output.

https://hackage.haskell.org/package/ghc-exactprint-0.3.1/docs/Language-Haske...

I don't think I'm quite sure what exactly you want, if you can give a specific use case then it will help me give a better answer. We also hang around in #haskell-refactorer if it is transforming source files that you are interested in.

Here is an example of how to use the library to insert a type signature for example.

https://github.com/alanz/ghc-exactprint/blob/master/examples/InsertSignature...

Happy to answer any more questions..

Matt

On Sat, Aug 8, 2015 at 1:04 AM, Corentin Dupont wrote:

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Hi Matthew, yes that's exactly that. I want to do exactly what you would do with a JSON file (read, write), but with a data format that would be valid Haskell (instead of valid javascript).

On Fri, Aug 7, 2015 at 8:06 PM, Matthew Pickering wrote:

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Hi Corentin,

I don't quite understand your question please can you explain a bit more. Do you want to read a valid haskell source file, perform some changes to the file and then print out a valid source file?

I am a bit confused about the bit about turing-completeness.

Matt

On Fri, Aug 7, 2015 at 7:55 PM, Corentin Dupont wrote:

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Hello! I'm wondering if it's possible to serialize some data to a format that is valid Haskell. In practice I would read a file like this:

module Foo where

myData :: MyData myData = MyData {name = "foo", descr = "test" ... }

Reading this into a program is easily feasible with Hint, for example. Then the program would modify some data and serialize it back to:

module Foo where

myData :: MyData myData = MyData {name = "bar", descr = "test2" ... }

In practice I think that the format should be a subset of Haskell that is not Turing-complete. A bit like JSON, which is a subset of Javascript but not Turing complete. Is it possible?

Thanks, Corentin

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