是否有 C++'s std::bind2nd 的内置 Haskell 等效项？
我缺少的是部分应用函数的第二个参数而不是第一个参数的能力。 当我想将函数传递给诸如 map 之类的东西，但不必每次都为其编写 lambda 时，这尤其有用。
我为此编写了自己的函数（定义如下，以防万一确实没有任何内置函数并且其他人对此感到好奇），但我真的很想知道 Prelude 中是否已经存在此函数习语，因为我更喜欢重用而不是重新发明。
这是我的定义和一个简单的例子：
bind2nd :: (a -> b -> c) -> b -> a -> c
bind2nd f b = \a -> f a b
foo :: Int -> Bool -> String
foo n b | b = show n
| otherwise = "blabla"
alwaysN :: Int -> String
alwaysN = bind2nd foo True
What I'm missing is the ability to partially apply the second argument of a function rather than the first. This is especially useful when I want to pass the function to something like map, but without having to write a lambda for it each time.
I wrote my own function for this (definition below, just in case there indeed isn't any built-in function for this and anyone else was curious), but I would really like to know if there already exists something in the Prelude for this idiom as I prefer to reuse rather than reinvent.
Here is my definition and a trivial example:
bind2nd :: (a -> b -> c) -> b -> a -> c
bind2nd f b = \a -> f a b
foo :: Int -> Bool -> String
foo n b | b = show n
| otherwise = "blabla"
alwaysN :: Int -> String
alwaysN = bind2nd foo True
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它称为
flip。示例：
为了将来参考，只需在 Hoogle 中搜索问题中的类型签名即可找到它，即
It's called
flip.Example:
For future reference, it could have been found by simply searching Hoogle for the type signature in your question, namely (a -> b -> c) -> b -> a -> c. :-)