T11667.hs:12:22: error:
    • Could not deduce (Num a) arising from the literal ‘42’
      from the context: Eq a
        bound by the signature for pattern synonym ‘Pat1’
        at T11667.hs:12:9-12
      Possible fix:
        add (Num a) to the "required" context of
          the signature for pattern synonym ‘Pat1’
    • In the pattern: 42
      In the pattern: Just 42
      In the declaration for pattern synonym ‘Pat1’

T11667.hs:18:28: error:
    • Couldn't match type ‘b’ with ‘Bool’
        arising from the "provided" constraints claimed by
          the signature of ‘Pat2’
      ‘b’ is a rigid type variable bound by
        the signature for pattern synonym ‘Pat2’ at T11667.hs:17:17-50
    • In the declaration for pattern synonym ‘Pat2’
    • Relevant bindings include y :: b (bound at T11667.hs:18:21)

T11667.hs:24:24: error:
    • No instance for (Show a)
        arising from the "provided" constraints claimed by
          the signature of ‘Pat3’
      In other words, a successful match on the pattern
        Just x
      does not provide the constraint (Show a)
    • In the declaration for pattern synonym ‘Pat3’

T11667.hs:31:16: error:
    • Could not deduce (Num a) arising from a use of ‘MkS’
      from the context: (Eq a, Show a)
        bound by the signature for pattern synonym ‘Pat4’
        at T11667.hs:31:1-21
      Possible fix:
        add (Num a) to the "required" context of
          the signature for pattern synonym ‘Pat4’
    • In the expression: MkS 42
      In an equation for ‘Pat4’: Pat4 = MkS 42