找出函數屬於哪個模塊

Question

在ghci（haskell）中是否有一個命令會告訴我一個函數屬於哪個模塊（加載模塊之外）。例如如果函數被調用whichMod，那麼它會工作如下：

Prelude>whichMod take 
Prelude 
Prelude>whichMod sort 
Data.List 

Answer 1

你想要:i指令（簡稱:info）。

Prelude> :i take 
take :: Int -> [a] -> [a] -- Defined in GHC.List 
Prelude> :i sort 

Top level: Not in scope: `sort' 
Prelude> :m +Data.List 
Prelude Data.List> :i sort 
sort :: Ord a => [a] -> [a]  -- Defined in Data.List 

正如你所建議的那樣，它只在函數處於當前加載的模塊中時才起作用。

請注意，您會被告知函數最初是在哪個模塊中定義的。 take在GHC.List中定義（至少在我的ghc副本中），但是從前奏中重新導出。你不知道你從哪個模塊導入它。

Answer 2

Prelude> :info take 
take :: Int -> [a] -> [a] -- Defined in `GHC.List' 

Answer 3

是的，存在功能：

Prelude> :! hoogle sort 
Data.List sort :: Ord a => [a] -> [a] 
Data.List sortBy :: (a -> a -> Ordering) -> [a] -> [a] 
Data.ByteString sort :: ByteString -> ByteString 
Data.ByteString.Char8 sort :: ByteString -> ByteString 
Data.Sequence sort :: Ord a => Seq a -> Seq a 
package sort-by-pinyin 
Data.Sequence sortBy :: (a -> a -> Ordering) -> Seq a -> Seq a 
GHC.Exts sortWith :: Ord b => (a -> b) -> [a] -> [a] 
package sorty 
package cabal-sort 
package external-sort 
Data.Graph.Inductive.Internal.Heap heapsort :: Ord a => [a] -> [a] 
package heapsort 
package natural-sort 
package NaturalSort 
Data.Graph topSort :: Graph -> [Vertex] 
Data.Graph.Inductive.Query.DFS topsort :: Graph gr => gr a b -> [Node] 
Data.Graph.Inductive.Query.DFS topsort' :: Graph gr => gr a b -> [a] 
Data.Sequence unstableSort :: Ord a => Seq a -> Seq a 
Data.Sequence unstableSortBy :: (a -> a -> Ordering) -> Seq a -> Seq a 
Prelude> _ 

你可以定義一個別名到您的「〜/ .ghci」配置文件

:def hoogle \str -> return $ ":! hoogle \"" ++ str ++ "\"" 

然後，你可以寫

Prelude> :hoogle sort 
Data.List sort :: Ord a => [a] -> [a] 
Data.List sortBy :: (a -> a -> Ordering) -> [a] -> [a] 
Data.ByteString sort :: ByteString -> ByteString 
Data.ByteString.Char8 sort :: ByteString -> ByteString 
Data.Sequence sort :: Ord a => Seq a -> Seq a 
package sort-by-pinyin 
Data.Sequence sortBy :: (a -> a -> Ordering) -> Seq a -> Seq a 
GHC.Exts sortWith :: Ord b => (a -> b) -> [a] -> [a] 
package sorty 
package cabal-sort 
package external-sort 
Data.Graph.Inductive.Internal.Heap heapsort :: Ord a => [a] -> [a] 
package heapsort 
package natural-sort 
package NaturalSort 
Data.Graph topSort :: Graph -> [Vertex] 
Data.Graph.Inductive.Query.DFS topsort :: Graph gr => gr a b -> [Node] 
Data.Graph.Inductive.Query.DFS topsort' :: Graph gr => gr a b -> [a] 
Data.Sequence unstableSort :: Ord a => Seq a -> Seq a 
Data.Sequence unstableSortBy :: (a -> a -> Ordering) -> Seq a -> Seq a 
Prelude> _