在詹金斯管道阶段如何更改变量值？

Question

我在jenkins管道的环境块中声明了一个默认值为='null'的变量，并试图在阶段中更改该值。

但是结果是不变的。

separa a xs = if length xs >= a then separaM a (drop a xs) ([take a xs]) else [xs]

separaM a xs yss = if length xs >= a then separaM a (drop a xs) (yss : (take a xs)) else separaM a [] (yss : xs)
separaM a [] yss = yss