I evaluated Joe's code using Patrick's explanation of parentheses-less parsing (in the REPL):
> say(so(any(<a b c> eq any(<c d>)))); False > say any(<a b c> eq any(<c d>)); any(any(False, False)) > Q1. Does it make any sense to call "any" on "any" (i.e. nested "any" calls)? Could this anti-pattern be used to generate a warning, i.e. 'Useless use of nested any-junctions, did you mean...' or something similar? > say any(<a b c> eq any(<c d>)); any(any(False, False)) > say any(<c d> eq any(<a b c>)); any(any(False, False, False)) > Q2. Swapping the first argument <a b c> to the binary infix operator 'eq' with the second argument <c d> results in two different code evaluations (above). Can this be used to alert the user to a potential violation of the commutative property of equality? Again, maybe useful for generating a warning (at least in the REPL), " Warning: Commutativity--code without parentheses evaluates differently based on LHS vs RHS ordering of arguments to "eq" operator... ." (note, the second suggestion won't help if each argument to the "any" calls surrounding 'eq' are an equivalent number of elements). HTH, Bill. On Sun, Jun 21, 2020 at 8:12 PM Patrick R. Michaud <pmich...@pobox.com> wrote: > > The "any" function is just like any other function taking an arbitrary list > of arguments (including user-defined functions). As such it parses with > lower precedence than comparison operators -- so "eq" binds more tightly than > "any". > > Thus > > say so any <a b c> eq any <c d>; > > parses like > > say(so(any(<a b c> eq any(<c d>)))); > > which is indeed False. > > I'm not exactly sure what sort of warning should go here, or how it'd be > detected. But perhaps others have ideas. > > Pm > > > On Sun, Jun 21, 2020 at 07:00:23PM -0700, Joseph Brenner wrote: > > I was just playing around with junctions a bit today, and I > > noticed that if you weren't religious about using parenthesis > > with them you could get quietly tripped up: > > > > say so any(<a b c>) eq any(<c d>); # True (as expected) > > say so any(<a b c>) eq any(<d e f>); # False (as expected) > > say so any <a b c> eq any <c d>; # False (something's wrong) > > > > Basically, you need the parens on that first use of any. > > > > Is there a reason you don't at least get a warning if you don't?
