Hello Ralf,
For me it's not an issue for the computational world.
I explain, and as an example, in the past I wrote code for FRiCAS with
GCL (lost code because of a hdd problem).
It was an interface to BLAS totally written with 'and' and 'or', I
love that and I am always inclined to do that instead, for example, of
using (progn ...), (if ...)... I sent the code privately to Tim but I
had no return, I guess this was because the code was unreadable :) A
game.
So, instead of using:
(if (that-is not-true)
(i-will-not-do-what-i-am-supposed-to-do)
; else
(i-will-do-my-job))
I used 'and' and 'or':
(or (and (that-is not-true) (i-will-not-do-what-i-am-supposed-to-do))
(i-will-do-my-jiob))
What I mean is, with imperative languages, statements are evaluated,
executed and change program's state, your example, and eventually
returns something. It's not from my point of view like pure
mathematical logic in its restrictive sense.
With mathematical logic, and also in mathematical articles, you read,
check, and use the theorem in another "article" if true
and interesting :)
So, even, if in pure boolean logic, 'and' and 'or' ('xor') are used
with only true and false, with imperative programming language this is
not only that. In your example, my point of view is that the important
thing to take into account is not the Type but what is done.
> zero? x or (x := x+1)
can be translated to
if not zero? x then x:= x+1
What I have in mind is for libraries and not for the interpreter who
shows if required and needs the output type.
So in your last example I agree with the interpreter it *evaluates*
the first statement but since it's false it *evaluates* the second
statement, but the output type of it is incorrect so it "barfs".
Just my two cents, and I don't know if I will be understood.
____
Greg
Le jeu. 26 janv. 2023 à 22:03, Ralf Hemmecke <[email protected]> a écrit :
>
> Is the following OK?
>
> (325) -> 4 or 3
>
> Argument number 1 to "or" must be a Boolean.
>
> (325) -> 4 or true
>
> Argument number 1 to "or" must be a Boolean.
>
> (325) -> true or 3
>
> (325) true
>
> (326) -> zero? 3 or 3
>
> Argument number 2 to "or" must be a Boolean.
>
> (326) -> zero? 0 or 3
>
> (326) true
>
> (327) -> true or "foo"
>
> (327) true
>
> Well, it is clear that a shortcut happens here, but I wonder whether we
> want the language to allow "or" to take non-boolean argument.
>
> This also is a problem in SPAD
>
> )abbrev package FOO Foo
> Foo: with
> foo: Integer -> Integer
> == add
> foo(x: Integer): Integer ==
> zero? x or
> return -13
> return x
>
> The following compiles and works as well.
>
> )abbrev package FOO Foo
> Foo: with
> foo: Integer -> Integer
> == add
> foo(x: Integer): Integer ==
> zero? x or (x := x+1)
> return x
>
> But what exactly is the type of
>
> zero? x or (x := x+1)
>
> ?
>
> Should I put this into the github issues?
>
> Ralf
>
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