call by need

求值策略 -... ... 2.2 传名调用( Call by name) 2.3 传需求调用( Call by need) 2.4 传宏展开调用( Call by macro expansion) ...

求值策略 -... ... 2.2 传名呼叫( Call by name) 2.3 传需求呼叫( Call by need) 2.4 传宏展开呼叫( Call by macro expansion) ...

...方式（也被称为正则序（normal order）或按需调用（call by need））。