Re: for or against equality, was Why are ambiguous grammars usually a bad idea?

On Monday, January 3, 2022 at 11:58:39 AM UTC-8, mac wrote:
> > [Interesting take. In reality, of couse, BASIC borrowed that from Fortran. Algol
> > used := for assignment, different from = for equality comparison. -John]


> Indeed.
> Unfortunately, assignment is probably the single most common operator.
> The ASCII committee should have kept the left-arrow character instead of
> replacing it with underscore.


The assignment statement in BASIC, at least the ones I know, has an
(optional) LET keyword, so it might say:


10 LET A=3


Most people leave it off, though.


Is PL/I the only language that uses = for both assignment and the relational operator?
Since expressions are not statements, it avoids the ambiguity that would otherwise occur.
I believe some BASIC also use = for both.


Underscore is a pretty useful character.


The two ASCII characters that don't exist in EBCDIC are ^ and ~.
Two EBCDIC characters that don't exist in ASCII are 𝇍 (cent)
and ¬ (logical NOT sign). Conversion tables usually cross
map those pairs. (PL/I, at least, uses ¬ and ¬= operators.)


[In original Dartmouth BASIC the LET was mandatory, but it was a considerably
smaller and fully compiled language than the later dialects. On the other
hand, PL/I made a fetish of nothing being a reserved word, e.g.


    IF IF = THEN THEN ELSE = BEGIN; ELSE END = IF;


-John]

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