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Don't Be Afraid of Types

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Re: Don't Be Afraid of Types

#21

Post by jandrewrogers »

motorest wrote: post #9
beders wrote: post #4

The issue is names. Every darn little thing in Java needs a name. If there is no good name, that's a hint that maybe you don't need a new type. Obligatory Clojure example: (defn full-name [{:keys [first-name last-name]}] (str first-name " " last-name)) This defines a function named `full-name`. The stuff between [] is the argument list. There's a single argument. The argument has no name. Instead it is using destruct…

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

Anonymous types are a thing in some languages. You also have adjacent concepts like anonymous namespaces in which you can dump types that require a name so that the names don’t leak out of the local context.

Sufficiently flexible namespaces do solve most of these problems. Java is kind of perverse though.

Re: Don't Be Afraid of Types

#22

Post by gleenn »

motorest wrote: post #9
beders wrote: post #4

The issue is names. Every darn little thing in Java needs a name. If there is no good name, that's a hint that maybe you don't need a new type. Obligatory Clojure example: (defn full-name [{:keys [first-name last-name]}] (str first-name " " last-name)) This defines a function named `full-name`. The stuff between [] is the argument list. There's a single argument. The argument has no name. Instead it is using destruct…

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

All types don't need names exactly like the Clojure example shows. There is no "type" for the argument, likely it's a map under the hood. And maps with keywords are used broadly across Clojure projects as a method of pass groups of data and no, you don't have to name that arbitrary collection of data. Rich Hickey has an amazing presentation on the silliness of a commonly used Java Web Request library where the vast majority of object types required could have just been little nested maps instead of creating a ton of bespoke like types that make it difficult to assemble and manipulate all the bits. The interface he roasts could be completely discarded an nearly no benefits lost in terms of readability or usability. Hickey is also famous for saying he would rather a few data structures and a 100 little algorithms instead of 10 data structures and 10 algorithms per data structure.

Re: Don't Be Afraid of Types

#23

Post by gleenn »

jandrewrogers wrote: post #21
motorest wrote: post #9

Earlier quoted context omitted.

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

Anonymous types are a thing in some languages. You also have adjacent concepts like anonymous namespaces in which you can dump types that require a name so that the names don’t leak out of the local context. Sufficiently flexible namespaces do solve most of these problems. Java is kind of perverse though.

Java:

Map m = new HashMap() {{ System.out.println("I am a unique subclass of HashMap with a single instance!");}};

Re: Don't Be Afraid of Types

#24

Post by jongjong »

I'm not a huge fan of types because they don't model the real world accurately. In the real world, most concepts which we describe with human language have many variations with optional properties and it's a pain and a waste of time to try to come up with labels to categorize each one... It induces people to believe that two similar concepts are distinct, when in fact, they are extremely similar and should share the same name. I hate codebases which have many different types for each concept... Just because they have a few properties that are different. It overcomplicates things and creates logical boundaries in the system before they are needed or well defined. It forces people to categorize concepts before they understand the business domain. People will argue that you can define types with optional properties, that's a fair point but you lose some type safety if you do that... If you can do away with some type safety (with regard to some properties), surely you can do away with it completely?

Re: Don't Be Afraid of Types

#25

Post by pjmlp »

noduerme wrote: post #18
motorest wrote: post #9

Earlier quoted context omitted.

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

I think Java culture had something to do with the ridiculously verbose names, but even more so the prevalence of Factory and Singleton paradigms in Java created these issues. Maybe because it was the first OO language that a lot of procedural coders came to in the 90s. Those patterns became sort of escape hatches to avoid reasoning about ownership, inheritance and scope. They're still common patterns for emergencies…

For whatever reason Java gets the blame for what was already common Smalltalk, C++, Clipper 5, Object Pascal, Actor, Eiffel, Objective-C,....before Oak idea turned into Java.

To the point many think the famous patterns book used Java, when it is all about Smalltalk and C++ patterns.

Re: Don't Be Afraid of Types

#26

Post by pjmlp »

9rx wrote: post #19
noduerme wrote: post #15

Huh. I don't see any conflict between loving OO-programming and also loving types. Isn't 9/10ths of OO just about consolidating your business logic into interfaces and types that you'd ideally want to re-use? I feel like if it's not, then people are using OO the wrong way.

You can love conflicting things, but the basis of OO programming, that which makes it object-oriented and not just object-based, is message passing, which sees messages flow between objects for inspection. That is inherently runtime behaviour which is at odds with static type enforcement.

As shown by The Art of Metaobject Protocol that is the genesis of CLOS, not really.

Re: Don't Be Afraid of Types

#27

Post by necovek »

Please be afraid of types.

On top of new cognitive load, introduction of redirection, and anti-patterns like pretend-simplification where you shuffle a bunch of unrelated parameters into a struct to make a function receive only a single argument (which quickly evolves into functions receiving parts of that struct they don't need, making use and testing much harder — I am surprised an article is really recommending this as a strategy), your types frequently get exposed to external users, and you need to start thinking about both backwards- and forwards-compatibility.

Benefits of types should be carefully balanced against the cost of introducing them, and while calling that "fear" might not be appropriate, it should be a conscious cost-benefit analysis.

Re: Don't Be Afraid of Types

#28

Post by re-thc »

noduerme wrote: post #18
motorest wrote: post #9

Earlier quoted context omitted.

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

I think Java culture had something to do with the ridiculously verbose names, but even more so the prevalence of Factory and Singleton paradigms in Java created these issues. Maybe because it was the first OO language that a lot of procedural coders came to in the 90s. Those patterns became sort of escape hatches to avoid reasoning about ownership, inheritance and scope. They're still common patterns for emergencies…

> I think Java culture had something to do with the ridiculously verbose names

People complain about this all the time but I'd rather take a verbose name than not knowing what is going on. Sometimes these naming conventions help.

Digging into older poorly named, structured and documented codebases is not fun.

Re: Don't Be Afraid of Types

#29

Post by MrBuddyCasino »

beders wrote: post #4

The issue is names. Every darn little thing in Java needs a name. If there is no good name, that's a hint that maybe you don't need a new type. Obligatory Clojure example: (defn full-name [{:keys [first-name last-name]}] (str first-name " " last-name)) This defines a function named `full-name`. The stuff between [] is the argument list. There's a single argument. The argument has no name. Instead it is using destruct…

This is easy and idiomatic in Golang with its combination of Interfaces and Duck Typing.

Why is it that dynamically typed languages usually develop static typing extensions (including Clojure)? Perhaps people don’t enjoy hunting down tedious spelling issues such as last-name vs family-name?

Re: Don't Be Afraid of Types

#30

Post by motorest »

noduerme wrote: post #18
motorest wrote: post #9

Earlier quoted context omitted.

> Every darn little thing in Java needs a name. Don't all types need names, regardless of what language you use? Look at typescript, and how it supports structural typing. They don't seem to have a problem with names. Why do you think Java has that problem when nominal type systems simplify the problem? > There's no need to declare a type ObjectWithFirstNameAndLastName. It would be quite silly. Naming things is hard,…

I think Java culture had something to do with the ridiculously verbose names, but even more so the prevalence of Factory and Singleton paradigms in Java created these issues. Maybe because it was the first OO language that a lot of procedural coders came to in the 90s. Those patterns became sort of escape hatches to avoid reasoning about ownership, inheritance and scope. They're still common patterns for emergencies…

> I think Java culture had something to do with the ridiculously verbose names, but even more so the prevalence of Factory and Singleton paradigms in Java created these issues.

It sounds like you're confusing things. Factories are a way to instantiate objects of a specific type a certain way. Singletons is just a restriction on how many instances of a type there can be.

These are not Java concepts, nor are they relevant to the topic of declaring and naming types.

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