"Indexed functor" AST (recursion schemes) #18
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After a few months experimenting I'm quite convinced the best way to do AST annotations and manipulation in Haskell is using ideas from recursion schemes. It allows having multiple variants of the AST (a 'bare' one using lists, one for the parser with position annotations and fast concat via
Data.Seq, another with custom metadata for exporting...) and once you have the instances, transforming between them is easier. Conceptually it is also simple and elegant.Closes #17