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by bsummer4
4068 days ago
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I went through some examples to make 100% sure that fold has different behavior than foldl/foldr: fold [[_ 4 _] 3 _] → f 4 (f 3 #)
fold2 f # [[_ 4 _] 3 _] → f (f # (f 4 #)) (f 3 #)
foldl f # [[_ 4 _] 3 _] → f (f # 4) 3
foldr f # [[_ 4 _] 3 _] → f 3 (f 4 #)
Reductions: fold [[_ 4 _] 3 _]
f (go [_ 4 _]) (f 3 (go []))
f 4 (f 3 (go []))
f 4 (f 3 #)
fold2 [[_ 4 _] 3 _]
fold3 f # [[_ 4 _] 3 _]
f (go [_ 4 _]) (f 3 (go _))
f (f (go _) (f 4 (go _))) (f 3 (go _))
f (f # (f 4 # )) (f 3 # )
f (f # (f 4 # )) (f 3 # )
f (f # (f 4 #)) (f 3 #)
foldl f # [[_ 4 _] 3 _]
go # [[_ 4 _] 3 _]
go (f (go # [_ 4 _]) 3) _
f (go # [_ 4 _]) 3
f (go (f (go # _) 4) _) 3
f (go (f # 4) _) 3
f (f # 4) 3
foldr f # [[_ 4 _] 3 _]
go # [[_ 4 _] 3 _]
go (f 3 (go # [_ 4 _])) _
f 3 (go # [_ 4 _])
f 3 (go (f 4 (go # _)) _)
f 3 (f 4 (go # _))
f 3 (f 4 #)
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