[Jprogramming] 50 j shades

[David Lambert]

50 Shades of j chapter 1 now says that rule is completely general.  I'm 
somewhat weak on j transformations and proofs, although what was there 
was incorrect because of a counterexample:

   every=.&>        NB. uses compose
   each=.&.>        NB. uses under
   rule =: (f every) -: >@(f each)

   NB. Is completely general?


thank you, Dave

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