以下不起作用,我该如何解决?
Prelude Control.Lens> (2, 3, 4) ^. alongside _1 _2
<interactive>:19:14:
Couldn't match type ‘(s0, s'0)’ with ‘(t0, t1, t2)’
Expected type: Getting (a, a') (t0, t1, t2) (a, a')
Actual type: LensLike
(Const (a, a')) (s0, s'0) (t3, t'0) (a, a') (a, a')
In the second argument of ‘(^.)’, namely ‘alongside _1 _2’
In the expression: (2, 3, 4) ^. alongside _1 _2
我想要的是(2, 3)
。