Full definition of .cabal file syntax

Question

I have googled extensively, and while I can find many examples of cabal files as well as good tutorials, I would like to have a proper grammar definition for the .cabal file format. Alas, I have not been able to find it. The more recent cabal documentation only mentions that its file format is backwards compatible -- with no links to the 'original' format with which it is compatible! Not useful.

Answer 1

a proper grammar definition for the .cabal file format.

The grammar is defined by its parser. I don't know of a formal specification.