That makes sense now. Thanks for the clarification! Kevin
On Tue, Feb 8, 2022 at 1:03 PM Alexander Burger <a...@software-lab.de> wrote: > Hi Kevin, > > > I may have encountered a possible bug, unless my understanding of @ is > > incorrect. It appears the value of @ is not restored in a prog1 body when > > another flow/logic statement occurs as the car of an expression within > the > > This is right. All flow functions which set '@' do *not* bind it. The > value is > simply set. > > > > Test Cases: > > > > (let (A0 (1) > > A1 (2 3) > > A2 'x) > > (prog1 (cdr A1) > > At this moment '@' is set to the result of evaluating (cdr A1). > > > ((if (sym? A2) 'set 'con) A2 A0) > > Now '@' was overwritten by 'if'. > > > '@' is bound only on the function call level. That is, '@' is restored to > the > caller's value when the function returns. > > But inside a function's body the rule is that > > 1. Functions with controlling expressions just set '@' to the result. > 'prog1' is > such a function. > > 2. Functions with conditional expressions set '@' to the result *IF* the > result > is non-NIL (otherwise they leave it untouched). > > > All this is described in more detail in > > https://software-lab.de/doc/ref.html#atres > > ☺/ A!ex > > -- > UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe >
