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Use Your Type System

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Re: Use Your Type System

#151

Post by 9rx »

js2 wrote: post #74
arrowsmith wrote: post #10

Earlier quoted context omitted.

FYI: Ruby is strongly typed, not loosely. > 1 + "1" (irb):1:in 'Integer#+': String can't be coerced into Integer (TypeError) from (irb):1:in ' ' from :168:in 'Kernel#loop' from /Users/george/.rvm/rubies/ruby-3.4.2/lib/ruby/gems/3.4.0/gems/irb-1.14.3/exe/irb:9:in ' ' from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in 'Kernel#load' from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in ' '

Good luck with this fight. I've had it on HN most recently 7 months ago, but about Python: https://news.ycombinator.com/item?id=42367644 A month before that: https://news.ycombinator.com/item?id=41630705 I've given up since then.

We've been reading comments like that since the internet was created (and no doubt in books before that). Why give up now?

Re: Use Your Type System

#152

Post by qcnguy »

frankus wrote: post #117

Swift has a typealias keyword but it's not really useful for this since two distinct aliased types with the same underlying type can be freely interchanged. Wrong code may look wrong but it will still compile. Wrapper structs are the idiomatic way to achieve this, and with ExpressibleByStringLiteral are pretty ergonomic, but I wonder if there's a case for something like a "strong" typealias ("typecopy"?) that indicat…

Haskell has this, it's called newtype.

In OOP languages as long as the type you want to specialize isn't final you can just create a subclass. It's cheap (no additional wrappers or boxes), easy, and you can specialize behavior if you want to.

Unfortunately for various good reasons Java makes String final, and String is one of the most useful types to specialize on.

Re: Use Your Type System

#153

Post by reactordev »

giraffe_lady wrote: post #123
ninetyninenine wrote: post #78

Earlier quoted context omitted.

This can be done in typescript. It’s not super well known because of typescripts association with frontend and JavaScript. But typescript is a language with one of the most powerful type systems ever. Among the popular languages like golang, rust or python typescript has the most powerful type system. How about a type with a number constrained between 0 and 10? You can already do this in typescript. type onetonine =…

Typescript's type system is turing complete, so you can do basically anything with it if this sort of thing is fun to you. Which is pretty much my problem with it: this sort of thing can be fun, feels intellectually stimulating. But the added power doesn't make coding easier or make the code more sound. I've heard this sort of thing called the "type puzzle trap" and I agree with that. I'll take a modern hindley milne…

Typescript’s type system can run Doom.

https://youtu.be/0mCsluv5FXA

Re: Use Your Type System

#154

Post by giraffe_lady »

reactordev wrote: post #153
giraffe_lady wrote: post #123

Earlier quoted context omitted.

Typescript's type system is turing complete, so you can do basically anything with it if this sort of thing is fun to you. Which is pretty much my problem with it: this sort of thing can be fun, feels intellectually stimulating. But the added power doesn't make coding easier or make the code more sound. I've heard this sort of thing called the "type puzzle trap" and I agree with that. I'll take a modern hindley milne…

Typescript’s type system can run Doom. https://youtu.be/0mCsluv5FXA

(derogatory)

Re: Use Your Type System

#155

Post by tomtom1337 »

somethingsome wrote: post #143

I'm curious about what you think about something, Supoose you make two simple types one for Kelvin K and the other for Fahrenheit F or degrees D. And you implement the conversions between them in the types. But then you have something like d: D = 10; For i=1...100000: k=f_Take_D_Return_K(d) d=g_Take_K_Return_D(k) end Then you will implicitly have many many automatic conversions that are not useful. How to handle this…

I interpret your question as «given that I am doing many conversions between temperature, because that makes it easier to write correct code, then I worry that my code will be slow because I am doing many conversions».

My response is: these conversions are unlikely to be the slow step in your code, don’t worry about it.

I do agree though, that it would be nice if the compiler could simplify the math to remove the conversions between units. I don’t know of any languages that can do that.

Re: Use Your Type System

#156

Post by [deleted] »

johnfn wrote: post #38
arrowsmith wrote: post #10

Earlier quoted context omitted.

FYI: Ruby is strongly typed, not loosely. > 1 + "1" (irb):1:in 'Integer#+': String can't be coerced into Integer (TypeError) from (irb):1:in ' ' from :168:in 'Kernel#loop' from /Users/george/.rvm/rubies/ruby-3.4.2/lib/ruby/gems/3.4.0/gems/irb-1.14.3/exe/irb:9:in ' ' from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in 'Kernel#load' from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in ' '

irb(main):001:0> a = 1 => 1 irb(main):002:0> a = '1' => "1" It doesn't seem that strong to me.

[deleted]

Re: Use Your Type System

#157

Post by yardstick »

abraxas wrote: post #79
default-kramer wrote: post #53

Earlier quoted context omitted.

I think checked exceptions were maligned because they were overused. I like that Java supports both checked and unchecked exceptions. But IMO checked exceptions should only be used for what Eric Lippert calls "exogenous" exceptions [1]; and even then most of them should probably be converted to an unchecked exception once they leave the library code that throws them. For example, it's always possible that your DB cou…

It's fine to let exceptions percolate to the top of the call stack but even then you likely want to inform the user or at least log it in your backend why the request was unsuccessful. Checked exceptions force both the handling of exceptions and the type checking if they are used as intended. It's not a problem if somewhere along the call chain an SQLException gets converted to "user not permitted to insert this data…

In my experience, the top level exception handler will catch all incl Throwable, and then inspect the exception class and any nested exception classes for things like SQL error or MyPermissionsException etc and return the politically correct error to the end user. And if the exception isn’t in a whitelist of ones we don’t need to log, we log it to our application log.

Re: Use Your Type System

#158

Post by ryandrake »

kwon-young wrote: post #142

This reminds me of the mp-units [1] library which aims to solve this problem focusing on the physical quantities. The use of strong quantities means that you can have both safety and complex conversion logic handled automatically, while having generic code not tied to single set of units. I have tried to bring that to the prolog world [2] but I don't think my fellow prolog programmers are very receptive to the idea ^…

I remember a long, long time ago, working on a project that handled lots of different types of physical quantities: distance, speed, temperature, pressure, area, volume, and so on. But they were all just passed around as "float" so you'd every so often run into bugs where a distance was passed where a speed was expected, and it would compile fine but have subtle or obvious runtime defects. Or the API required speed in km/h, but you passed it miles/h, with the same result. I always wanted to harden it up with distinct types so we could catch these problems during development rather than testing, but I was a junior guy and could never articulate it well and justify the engineering effort, and nobody wanted to go through the effort of explicitly converting to/from primitive types to operate on the numbers.

Re: Use Your Type System

#159

Post by materiallie »

default-kramer wrote: post #53
abraxas wrote: post #37

An adjacent point is to use checked exceptions and to handle them appropriate to their type. I don't get why Java checked exceptions were so maligned. They saved me so many headaches on a project where I forced their use as I was the tech lead for it. Everyone hated me for a while because it forced them to deal with more than just the happy path but they loved it once they got in the rhythm of thinking about all the…

I think checked exceptions were maligned because they were overused. I like that Java supports both checked and unchecked exceptions. But IMO checked exceptions should only be used for what Eric Lippert calls "exogenous" exceptions [1]; and even then most of them should probably be converted to an unchecked exception once they leave the library code that throws them. For example, it's always possible that your DB cou…

Put another way: errors tend to either be handled "close by" or "far away", but rarely "in the middle".

So Java's checked exceptions force you to write verbose and pointless code in all the wrong places (the "in the middle" code that can't handle and doesn't care about the exception).

Re: Use Your Type System

#160

Post by librasteve »

ryandrake wrote: post #158
kwon-young wrote: post #142

This reminds me of the mp-units [1] library which aims to solve this problem focusing on the physical quantities. The use of strong quantities means that you can have both safety and complex conversion logic handled automatically, while having generic code not tied to single set of units. I have tried to bring that to the prolog world [2] but I don't think my fellow prolog programmers are very receptive to the idea ^…

I remember a long, long time ago, working on a project that handled lots of different types of physical quantities: distance, speed, temperature, pressure, area, volume, and so on. But they were all just passed around as "float" so you'd every so often run into bugs where a distance was passed where a speed was expected, and it would compile fine but have subtle or obvious runtime defects. Or the API required speed i…

this was very much my intent with https://raku.land/zef:librasteve/Physics::Measure
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