在书籍《Learn You a Haskell for Great Good》的关于函子的章节中,有一个涉及
为什么后者不是
Either
的例子,我不太理解:ghci> fmap (replicate 3) (Right "blah")
Right ["blah","blah","blah"]
ghci> fmap (replicate 3) (Left "foo")
Left "foo"
为什么后者不是
Left ["foo", "foo", "foo"]
呢?