{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
module Examples.SortRows where
import Data.Massiv.Array as A
import Data.Massiv.Array.Manifest.Vector as A
import Data.Massiv.Core.Scheduler
import Data.Typeable
import Data.Vector.Algorithms.Merge
import Data.Vector.Generic as VG
import Data.Vector.Generic.Mutable as VGM
import System.IO.Unsafe
sortRows ::
forall r e v.
(Ord e, Typeable v, A.Mutable r Ix2 e, VG.Vector v e, ARepr v ~ r, VRepr r ~ v)
=> Array r Ix2 e
-> Array r Ix2 e
sortRows arr = unsafePerformIO $ do
mv :: VG.Mutable v RealWorld e <- VG.thaw (A.toVector arr :: v e)
let comp = getComp arr
sz@(m :. n) = size arr
case comp of
Seq -> do
loopM_ 0 (< m) (+ 1) $ \i -> sort $ VGM.slice (toLinearIndex sz (i :. 0)) n mv
ParOn wIds ->
withScheduler_ wIds $ \scheduler -> do
loopM_ 0 (< m) (+ 1) $ \i ->
scheduleWork scheduler $ sort $ VGM.slice (toLinearIndex sz (i :. 0)) n mv
v :: v e <- VG.unsafeFreeze mv
return $ A.fromVector comp sz v
我理解为什么传递function parseData (data) {
return (data && JSON.parse(data)) || [];
}
var arrayOfObjects;
var defaultValue = parseData(arrayOfObjects);
console.log(defaultValue); // "[]"
arrayOfObjects = [{id: 1}, {id: 2}];
var stringified = JSON.stringify(arrayOfObjects);
var parsedValues = parseData(stringified);
console.log(parsedValues); // "[{id: 1}, {id: 2}]"
console.log(Array.isArray(parsedValues)); // "true"会返回后备空数组。
但是，为什么将定义的值传递给undefined却返回一个数组而不是布尔值？
parseData()中的逻辑AND运算符是否会强制将两个操作数合并为data && JSON.parse(data)？