ddrone / auto-parser

Learning to use GHC.Generics

auto-parser

In Haskell, implementing a simple way to read your custom datatypes from text is as easy as writing deriving Read in the datatype definition. However, there does not seem to be an easy way to make this parsing method to provide some parsing diagnostics.

Potential solution: re-implement parsing the same format as deriving Read using parser combinators and datatype-generic programming. This repository is an attempt of implementing that solution, currently work-in-progress.

Tasks

• Make AutoPrinter work for record types
• Make AutoParser work for record types
• Make AutoPrinter and AutoParser work in presence of infix data constructors

Notes

Generic representation of record type

ghci> :t from foo
from foo
  :: D1
       (MetaData "Foo" "Playground" "auto-parser-0.1.0.0-inplace" False)
       (C1
          (MetaCons "Foo" PrefixI True)
          (S1
             (MetaSel
                (Just "bar") NoSourceUnpackedness NoSourceStrictness DecidedLazy)
             (Rec0 Int)
           :*: (S1
                  (MetaSel
                     (Just "baz") NoSourceUnpackedness NoSourceStrictness DecidedLazy)
                  (Rec0 Int)
                :*: S1
                      (MetaSel
                         (Just "quux") NoSourceUnpackedness NoSourceStrictness DecidedLazy)
                      (Rec0 [Int]))))