29 Jan
2021
29 Jan
'21
6:27 a.m.
On Jan 29, 2021, at 7:27 AM, Gavin Scott via cctalk
<cctalk at classiccmp.org> wrote:
On Fri, Jan 29, 2021 at 6:11 AM Peter Corlett via cctalk
<cctalk at classiccmp.org> wrote:
True, although right to left is not a natural way to read mathematical formulas. The
reason APL uses right to left is that the designers apparently were unwilling to change
the direction of the assignment operator, so everything else had to follow. Another
language that doesn't have precedence avoided this issue by changing assignment to
match the others, i.e., everything is left to right. That is POP-2, a language out of the
U of Edinborough I remember from an AI class. So it would do stuff like:
a + 1 * 5 -> b
which in C would be
b = (a + 1) * 5;
and is definitely easier to read than the APL equivalent.
paul
Secondly, beyond BODMAS, the meaning and
precedence of random symbols is
unclear to casual readers.
An issue that plagues other operator-rich languages, but not APL since
APL follows a strict right-to-left evaluation order for ALL operators
(no BODMAS in sight). You can use parentheses to affect it, but it's
not as hard to figure out a complex APL expression as one might
naively expect at first glance.