On 11/24/2019 5:30 PM, Jonathan Simpson wrote:
The documentation for char=? leaves the impression that it takes a
minimum of two arguments:
https://docs.racket-lang.org/reference/characters.html?q=expand#%28def._%28%28quote._~23~25kernel%29._char~3d~3f%29%29
If a single character is passed as argument 1, char=? returns true. To
me, '=' implies at least two things to compare. The other functions in
this family appear to behave the same way.
There is a note saying that since 7.0 the functions accept one
argument. Any reason for this change? At the very least I think the
documentation could make this clearer(probably because the docs were
originally written when it required two arguments).
-- Jonathan
I don't know the developers' reasoning, but I can guess.
Predicates already were variadic taking 2 or more arguments (at least
since R3RS, circa 1986), and they behave like a fold/reduce with an
implied base/identity value. I think the idea is that they should work
with any non-empty list of arguments.
FWIW, Common Lisp's predicates always have behaved in this way.
YMMV,
George
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