If I may join Circular function in asking annoying questions (co-sinning as it were), what exactly are the semantics of optional variables?<br>It appears from experiment that they are evaluated sequentially in environments containing the previously declared parameters, kind of like let*.<br>
In fact, it appears that evaluation of optional parameters can safely[*] mutate earlier optional and non-optional parameters.<br><br><br>[*] but not necessarily sanely. I've probably been writing too much R code <br>
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