Haskellタプルは実質15個まで

タプルでshowやeqが定義されているのは15個まで

タプル15個

 > type Foo = (Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool)
  > (True, False, True, True, True, True, True, True, True, True, True, True, True, True, True) :: Foo
(True,False,True,True,True,True,True,True,True,True,True,True,True,True,True)

タプル16個

> type Foo = (Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool, Bool)
 > (True, False, True, True, True, True, True, True, True, True, True, True, True, True, True, True) :: Foo

<interactive>:65:1: error:
    ? No instance for (Show Foo) arising from a use of ‘print’
    ? In a stmt of an interactive GHCi command: print it
 >