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  1. Prelude> let f (x:xs) = (x:xs)
  2.  
  3. ==================== Simplified expression ====================
  4. GHC.Base.returnIO
  5.   @ [()]
  6.   (GHC.Types.:
  7.      @ ()
  8.      ((\ (@ a_a131) (ds_d13a :: [a_a131]) ->
  9.          case ds_d13a of _ [Occ=Dead] {
  10.            [] ->
  11.              Control.Exception.Base.patError
  12.                @ 'GHC.Types.PtrRepLifted
  13.                @ [a_a131]
  14.                "<interactive>:4:5-21|function f"#;
  15.            : x_a12Q xs_a12R -> GHC.Types.: @ a_a131 x_a12Q xs_a12R
  16.          })
  17.       `cast` (UnsafeCo representational
  18.                 (forall a_a131. [a_a131] -> [a_a131]) ()
  19.               :: ((forall a_a131. [a_a131] -> [a_a131]) :: *) ~R# (() :: *)))
  20.      (GHC.Types.[] @ ()))
  21.  
  22.  
  23. Prelude> let f a@(x:xs) = a
  24.  
  25. ==================== Simplified expression ====================
  26. GHC.Base.returnIO
  27.   @ [()]
  28.   (GHC.Types.:
  29.      @ ()
  30.      ((\ (@ t_a13D) (a_a13s :: [t_a13D]) ->
  31.          case a_a13s of wild_X3 {
  32.            [] ->
  33.              Control.Exception.Base.patError
  34.                @ 'GHC.Types.PtrRepLifted
  35.                @ [t_a13D]
  36.                "<interactive>:5:5-18|function f"#;
  37.            : x_a13t xs_a13u -> wild_X3
  38.          })
  39.       `cast` (UnsafeCo representational
  40.                 (forall t_a13D. [t_a13D] -> [t_a13D]) ()
  41.               :: ((forall t_a13D. [t_a13D] -> [t_a13D]) :: *) ~R# (() :: *)))
  42.      (GHC.Types.[] @ ()))
  43.  
Not running #stdin #stdout 0s 0KB
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https://ideone.com/6r6LpA
language:
Text (text 6.10)
created:
6 years ago
visibility:
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