Hello, I’ve made a built-in function that takes a list and returns a list: `type family MySet [k] -> [k]`. I think I did something wrong because right now I’m getting an exception like that: ``` Extracted [Int, Bool, Char] — input list 1 List_ty '[Bool, Char, Int] — sorted list 1 Extracted [Int, Bool, Char] — input list 2 (?) List_ty '[Bool, Char, Int] — sorted list 2 (?) ghc: panic! (the 'impossible' happened) (GHC version 8.4.2 for x86_64-apple-darwin): ASSERT failed! Bad coercion hole co_a2QJ: MySet '[Bool, Char, Int] nominal (MySet '[Int, Bool, Char] :: [*]) ~# ('[Bool, Char, Int] :: [*]) Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1208:22 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcMType.hs:306:25 in ghc:TcMType Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1206:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcMType.hs:306:25 in ghc:TcMType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug ``` when I’m trying to check the ~ relation: ``` test :: Proxy (GHC.TypeLits.MySet '[Int, Bool, Char]) -> Proxy (GHC.TypeLits.MySet '[Int, Bool, Char]) test = id ``` But when I do something like that: ``` test :: (GHC.TypeLits.MySet '[Int, Bool, Char] ~ as, GHC.TypeLits.MySet '[Int, Bool, Char] ~ bs) => Proxy as -> Proxy bs test = id ``` everything is fine. I think the problem is that I tried to follow TcTypeNats#typeSymbolCmpTyCon etc style but all the functions there have two inputs and one output with built-in kind (I tried to do [k] kind by myself), so probably I understood something wrong. Could someone give me a hint what I did wrong, please? I can show my code if needed. Thank you for your time, Alice.