support [r| { a,b :: T } |] syntax

[aavogt]

Currently it fails with Parser failure: Failed reading: satisfy. Contexts: ["type'","'('"]. which could be a better message too.

[rabipelais]

Would this be equivalent to [r| { a :: T, b :: T } |]?

[aavogt]

yes just like how in haskell you can write data T t = Con { a, b :: t }

[nikita-volkov]

Concerning the error message see #4.

Concerning getting this syntax supported, I'm conflicted about this. On one hand, as long as it concerns only the type-level syntax, I don't see this creating any ambiguity. OTOH I don't see much usefulness in this syntax and instead see it as more of pertaining to feature bloat. So my vote is negative on this one. I won't stand in your way if you decide to implement it, however I must inform you that the preprocessor reimplementation of the library will initially be lacking this feature either way, since it's a complete rewrite of the related part of the library.