Hi Jon,
> If you read the docs carefully, you may know that (gt0 X) and (> X
> 0) are NOT equivalent. This is my small observation today:
>
> X: 1 T
> -------------------
> (gt0 X) -> 1 NIL
>
> (> X 0) -> T T
Yes, very true. Thanks for reminding about it!
This is in fact the intended behavior. Perhaps I should add some
explanation.
1. '>' is a function for general comparisons, not only for numbers but
for any data type. As described in
http://software-lab.de/doc/ref.html#cmp
all data in PicoLisp have a well-defined ordinal relationship. This
defines that
NIL < numbers < symbols < lists < T
As a result, both '1' and 'T' are greater than '0'.
2. 'gt0', on the other hand, is a predicate for "numbers greater zero":
http://software-lab.de/doc/refG.html
Thus, it returns the numeric argument for '1', and 'NIL' for any non-
numeric argument.
BTW, eeturning the argument itself instead of simply 'T' is very
convenient in many situations, e.g.
(while (gt0 (foo)) # No need to store the result of (foo)
(bar @) ) # in a local variable
> Have a nice weekend!
Thanks, you too!
♪♫ Alex
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