order of operations

[Frank Erickson]

I'm getting conformability errors when I go from :+ with rows to :- with columns:

t=1::10
p=1..3

// conformability error
q = J(length(t),length(p),0) :+ 8 :+ (3..1)/10 :- .5*log(p) :- t/2

// parentheses work 
q = ( J(length(t),length(p),0) :+ 8 :+ (3..1)/10 :- .5*log(p) ) :- t/2

// columns before rows works
q = - t/2 :+ J(length(t),length(p),0) :+ 8 :+ (3..1)/10 :- .5*log(p)

I'm surprised that parentheses are needed here. Doesn't Mata evaluate :+ and :- sequentially, left-to-right?