Occasionally someone will be annoyed that Julia requires an actual true or false value in conditionals, whereas many dynamic languages (including Lisps) allow arbitrary values in conditions and have rules about what count as “truthy” or “falsey” in that context. Many static languages even allow a de…

[image] StefanKarpinski: Julia could easily do something along these lines by having a Base.istruthy(x) generic function that types can “register” themselves with; conditionals would implicitly call Base.istruthy(cond) to check which branch should be evaluated. If someone is feeling especiall…

[image] giordano: > [42].every(() => {true}) false I see it now, hahaha. It lacks a return, so all the “returns” are undefined which is falsy…

I recommend people who ask me the similar thing to explain to me the following Python code: >>> all([]) True >>> all([[]]) False >>> all([[[]]]) True

I love the fact that Julia disallows non-Bool types in conditions, it saves a lot of bugs.

[image] suavesito: I see it now, hahaha. It lacks a return , so all the returns are undefined which is falsy… That, or remove the braces (but in my case I had a more complicated expression so removing braces wasn’t an option) because arrow functions do not magically guess what or when you w…

[image] StefanKarpinski: You hopefully get the point: it’s almost as if these languages were just making up random shit and then claiming that it’s obvious. If you want to know if a number is zero, compare it to zero. If you want to know if a string or array are empty, check if they’re empty. …

All these fancy-schmancy notions of “correctness”, “consistency” and “error resistance” in Julia feel so 20th century to me. Those other languages have apparently embraced postmodern relativism, that truth can be whatever feels right to you depending on your viewpoint and daily mood. That approach i…

jnz/jz are very useful for pointers. if p = function_with_optional_result(...) # use p, as it is non-null end is a common pattern in, for example, the LLVM code base. I’m not saying this is a better convention than explicit optional types (or returning nothing that’ll throw an error if you tr…

[image] bkamins: explain to me the following Python code In the first example, Julia does the same thing, which is common in logical systems. julia> all([]) true all([[]]) is false because the only value is an empty list, which is falsy. In [4]: x = [] In [5]: bool(x) Out[5]: False In [6…

As much as I agree with the boolean/nonboolean distinction, I often wish Julia had gone one step further and not considered booleans to be integers. julia> supertypes(Bool) (Bool, Integer, Real, Number, Any) julia> true + false 1

On the arbitrariness of truth(iness)

Internals & Design

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On the arbitrariness of truth(iness)

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