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| -rw-r--r-- | libraries/base/GHC/Base.hs | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/libraries/base/GHC/Base.hs b/libraries/base/GHC/Base.hs index 5a9d38f147..508edb71e2 100644 --- a/libraries/base/GHC/Base.hs +++ b/libraries/base/GHC/Base.hs @@ -523,6 +523,9 @@ structure of @f@. Furthermore @f@ needs to adhere to the following: Note, that the second law follows from the free theorem of the type 'fmap' and the first law, so you need only check that the former condition holds. +See <https://www.schoolofhaskell.com/user/edwardk/snippets/fmap> or +<https://github.com/quchen/articles/blob/master/second_functor_law.md> +for an explanation. -} class Functor f where |