Truth Functional Logic for Hackers(lagomor.ph)
lagomor.ph
Truth Functional Logic for Hackers
https://lagomor.ph/2025/02/truth-functional-logic-for-hackers-part-one/
14 comments
I don't get it. Isn't this what compilers are for? So I don't have to rewrite my code in an equivalent but stupider way just to get a marginal performance gain.
I think what you're missing is that the premise of a hardware bug is just a frame story for a lesson in manipulating logical statements, which is the main point.
Okay, it's just incredibly contrived.
You might as well replace "hardware bug" with "a wizard put a curse on the OR operator" or "the president put a tariff on OR imports", and it would be more believable.
You might as well replace "hardware bug" with "a wizard put a curse on the OR operator" or "the president put a tariff on OR imports", and it would be more believable.
Presumably, the compiler is not aware of the hardware bug in the OR operation, so it won't do any transforms to avoid using the OR operation.
Okay so... then patch the compiler? This is basic stuff.
If it were "basic stuff", then you probably weren't using a high performance compiler to begin with.
In this blog article from 2021, I warn about making this change without appropriate care, as it has been a source of common bugs: https://danverbraganza.com/writings/de-morgans-flaw-perform-...
> At every place X in the following expression, introduce a boolean negation if there isn’t one (or, equivanently remove one if there is), and
I think it should read:
At every place X in the following expression, introduce a boolean negation if there isn’t one and remove one if there is, and
Maybe even better:
At every place X in the following expression, introduce a boolean negation. If you get two concecutive NOT's, they can be removed.
Next, I don't see how
I think it should read:
At every place X in the following expression, introduce a boolean negation if there isn’t one and remove one if there is, and
Maybe even better:
At every place X in the following expression, introduce a boolean negation. If you get two concecutive NOT's, they can be removed.
Next, I don't see how
timespent <= duration
duration > time_spent
?My first thought was to rewrite it without any or and operation.
just return early from if statement.
If user is blacklisted return access denied; If account is expired return access denied; If no conditions match return access granted;
Wouldn't that be more effective?
If user is blacklisted return access denied; If account is expired return access denied; If no conditions match return access granted;
Wouldn't that be more effective?
You are touching on an inherent truth in TFL, which is that there are nearly infinite equivalent statements for any logical sentence.
The idea for the article was to make a real example of logical equivalence, as books on the subject stay pretty abstract. - like others have mentioned, in the real world there are smarter choices to be made.
The idea for the article was to make a real example of logical equivalence, as books on the subject stay pretty abstract. - like others have mentioned, in the real world there are smarter choices to be made.
The code blocks’ font size varies line by line on mobile. Hint: set it to be smaller than the body text size because monospace fonts tend to be a bit larger than proportional ones.
You've discovered a CSS issue that I did not notice for seven years.
Thanks.
The issue was that for some reason, different types of code had different font size settings.
Thanks.
The issue was that for some reason, different types of code had different font size settings.
https://openlogicproject.org/