Sample GHC Core output when dealing with multiple classes

A.hs

module A where

class Foo a where foo :: a -> String

instance Show a => Foo [a] where foo = ($ "") . showList

B.hs

module B where

class Bar a where foo :: a -> a

instance Bar [a] where foo = reverse

Main.hcr

func [InlPrag=NOINLINE]
  :: forall a_aIx. (Foo a_aIx, Bar a_aIx) => a_aIx -> String
[GblId, Arity=2, Str=DmdType]
func =
  \ (@ a5_aMq) ($dFoo_aMs :: Foo a5_aMq) ($dBar_aMt :: Bar a5_aMq) ->
    . @ a5_aMq
      @ String
      @ a5_aMq
      ($dFoo_aMs
       `cast` (A.NTCo:Foo[0] <a5_aMq>_N
               :: Foo a5_aMq ~R# (a5_aMq -> String)))
      ($dBar_aMt
       `cast` (B.NTCo:Bar[0] <a5_aMq>_N
               :: Bar a5_aMq ~R# (a5_aMq -> a5_aMq)))

a_rPr :: Int
[GblId, Caf=NoCafRefs, Str=DmdType]
a_rPr = GHC.Types.I# 1

a1_rPY :: Int
[GblId, Caf=NoCafRefs, Str=DmdType]
a1_rPY = GHC.Types.I# 2

a2_rPZ :: Int
[GblId, Caf=NoCafRefs, Str=DmdType]
a2_rPZ = GHC.Types.I# 3

a3_rQ0 :: [Int]
[GblId, Caf=NoCafRefs, Str=DmdType]
a3_rQ0 = GHC.Types.: @ Int a2_rPZ (GHC.Types.[] @ Int)

a4_rQ1 :: [Int]
[GblId, Caf=NoCafRefs, Str=DmdType]
a4_rQ1 = GHC.Types.: @ Int a1_rPY a3_rQ0

lst :: [Int]
[GblId, Caf=NoCafRefs, Str=DmdType]
lst = GHC.Types.: @ Int a_rPr a4_rQ1

main :: IO ()
[GblId, Str=DmdType]
main =
  putStrLn
    (func
       @ [Int] (A.$fFoo[] @ Int GHC.Show.$fShowInt) (B.$fBar[] @ Int) lst)

:Main.main :: IO ()
[GblId, Str=DmdType]
:Main.main = GHC.TopHandler.runMainIO @ () main

Main.hs

module Main where

import A
import B

func :: (Foo a, Bar a) => a -> String
func = A.foo . B.foo
{-# NOINLINE func #-}

lst :: [Int]
lst = [1,2,3]

main = putStrLn (func lst)