Desugared:
Test.f :: for all d. [d] -> Int {- 0 MkInt deriving ( )-} =
    /\ t78 -> \ x.88 :: [t78] ->
	let ds.89 :: [t78] = x.88 :: [t78] in
	let
	  fail.90 :: Int {- 0 MkInt deriving ( )-} =
	      ({-CoTyApp-} error :: for all a.
					[Char {- 0 MkChar deriving ( )-}] -> a
		   Int {- 0 MkInt deriving ( )-})
		  "\"ds030.hs\", line 5: pattern-matching failed in case\n"S in
	let
	  fail.92 :: Int {- 0 MkInt deriving ( )-} =
	      let
		dict.91 :: <Num {- Num -} <Num {- Num -} Int {- 0 MkInt deriving ( )-}>> =
		    dfun.Num.Int :: <Num {- Num -} Int {- 0 MkInt deriving ( )-}>
	      in 
		MkInt :: IntPrim{- StgInt -} -> Int {- 0 MkInt deriving ( )-}!
		    4#
	in 
	  case ds.89 :: [t78] of {
	    [a] {- 1 a Nil, : deriving ( )-}
	    Nil :: for all a. [a] ->
		let
		  dict.93 :: <Num {- Num -} <Num {- Num -} Int {- 0 MkInt deriving ( )-}>> =
		      dfun.Num.Int :: <Num {- Num -} Int {- 0 MkInt deriving ( )-}>
		in 
		  MkInt :: IntPrim{- StgInt -} -> Int {- 0 MkInt deriving ( )-}!
		      3#
	    _ ->  fail.92 :: Int {- 0 MkInt deriving ( )-}
	  }