相关疑难解决方法(0)

考虑以下程序.它永远运行并没有任何用处,但ghci中的内存消耗是不变的:

--NoExplode.hs
module Main (main) where

test :: [Int] -> IO()
test lst = do
  print "test"
  rList lst

rList :: [Int] -> IO ()
rList [] = return ()
rList (x:xs) = do
  rList xs

main = do
  test [1..]

现在考虑以上的以下简单修改版本.当这个程序在ghci中运行时,内存会爆炸.唯一的区别是print "test"现在分配给x了do块test.

--Explode.hs
module Main (main) where

test :: [Int] -> IO()
test lst = do
  x <- print "test"
  rList lst

rList :: [Int] -> IO ()
rList [] = …