6 ms·

(The following comment may not have anything to do with Haskell’s use of the word “name,” but I’ve wondered about this for a long time.) Forcing someone to wri

(The following comment may not have anything to do with Haskell’s use of the word “name,” but I’ve wondered about this for a long time.) Forcing someone to write iFoo instead of foo isn’t type safety, but it’s a certain kind of safety that I haven’t seen clearly spelled out. Actually I recall Joel on Software mentioning it once. I don’t like it, but it’s always seemed interesting. Another example is in lisp: *current-input-port* to indicate that a variable is dynamic, you can end it with an asterisk. But this is only a convention. I’ve always felt that LET should automatically do dynamic binding for any name that ends with . But then of course that runs into surprising corner cases when the user wants to e.g. write foo-+ foo-/ foo- foo— You could argue that names aren’t type safety, but I would disagree that they aren’t any kind of safety. A good naming convention is one of the safest ways to program in an otherwise hostile domain. But that raises the question: what kind of safety is it? I’m not sure it even has a name, other than Hungarian notation, which is both imprecise and not sufficiently general for the concept. EDIT: Ah, the post was “Making Wrong Code Look Wrong” by Joel on Software: https://www.joelonsoftware.com/2005/05/11/making-wrong-code-look-wrong/ https://www.joelonsoftware.com/2005/05/11/making-wrong-code-... (with discussion from 11mo ago: https://news.ycombinator.com/item?id=21482993 https://news.ycombinator.com/item?id=21482993) The idea really should have a name.

pwm 6y ago
> Forcing someone to write iFoo instead of foo isn’t type safety, but it’s a certain kind of safety The term I'd use (at least from the top of my head) is hygiene. The article uses the word safety in a restrictive sense, ie. preventing errors. Forcing iFoo instead of foo, to me, is more about hygiene where one could still potentially make an (accidental or deliberate) error but that would go against said hygiene. Maybe another way to put it is that safety prevent misuse while hygiene guides correct use. Or another is that with safety the letter and spirit of the law are one and the same while with hygiene it's not. Haskell's `newtype` is an amazing tool for (proactive) hygiene and, as the article says, a limited tool for safety. By proactive hygiene I mean that if you have: bmi :: Float -> Float -> Float Looking at it you don't know what those params are. They are all just `Float`s. There's not vocabulary to them. Meanwhile here: newtype Height = MkHeight Float newtype Weight = MkWeight Float bmi :: -> Height -> Weight -> Float It is both clear what they are as well as the compiler will prevent you from passing `Weight` as the 1st param. Now it's not safety as you can still wrap the wrong `Float` as `Height` but that would go against the hygiene.

pwm 6y ago

> Forcing someone to write iFoo instead of foo isn’t type safety, but it’s a certain kind of safety The term I'd use (at least from the top of my head) is hygiene. The article uses the word safety in a restrictive sense, ie. preventing errors. Forcing iFoo instead of foo, to me, is more about hygiene where one could still potentially make an (accidental or deliberate) error but that would go against said hygiene. Maybe another way to put it is that safety prevent misuse while hygiene guides correct use. Or another is that with safety the letter and spirit of the law are one and the same while with hygiene it's not. Haskell's `newtype` is an amazing tool for (proactive) hygiene and, as the article says, a limited tool for safety. By proactive hygiene I mean that if you have: bmi :: Float -> Float -> Float Looking at it you don't know what those params are. They are all just `Float`s. There's not vocabulary to them. Meanwhile here: newtype Height = MkHeight Float newtype Weight = MkWeight Float bmi :: -> Height -> Weight -> Float It is both clear what they are as well as the compiler will prevent you from passing `Weight` as the 1st param. Now it's not safety as you can still wrap the wrong `Float` as `Height` but that would go against the hygiene.