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Use Your Type System

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Re: Use Your Type System

#2

Post by zeroCalories »

I generally agree, but I think the real strength in types come from the way in which they act as documentation and help you refactor. If you see a well laid out data model in types you supercharge your ability to understand a complex codebase. Issues like the one in the example should have been caught by a unit test.

Re: Use Your Type System

#3

Post by pclowes »

I like this. Very much falls into the "make bad state unrepresentable".

The issues I see with this approach is when developers stop at this first level of type implementation. Everything is a type and nothing works well together, tons of types seem to be subtle permutations of each other, things get hard to reason about etc.

In systems like that I would actually rather be writing a weakly typed dynamic language like JS or a strongly typed dynamic language like Elixir. However, if the developers continue pushing logic into type controlled flows, eg:move conditional logic into union types with pattern matching, leverage delegation etc. the experience becomes pleasant again. Just as an example (probably not the actual best solution) the "DewPoint" function could just take either type and just work.

Re: Use Your Type System

#5

Post by jjice »

Does anyone know the term for this? I had "Type Driven Development" in my head, but I don't know if that's a broadly used term for this.

It's a step past normal "strong typing", but I've loved this concept for a while and I'd love to have a name to refer to it by so I can help refer others to it.

Re: Use Your Type System

#6

Post by jshxr »

jjice wrote: post #5

Does anyone know the term for this? I had "Type Driven Development" in my head, but I don't know if that's a broadly used term for this. It's a step past normal "strong typing", but I've loved this concept for a while and I'd love to have a name to refer to it by so I can help refer others to it.

I've seen it being referred to as "New Type Pattern" or "New Type Idiom" in quite some places. For example in the rust-by-example book [1].

[1] https://doc.rust-lang.org/rust-by-example/generics/new_types...

Re: Use Your Type System

#9

Post by frou_dh »

jjice wrote: post #5

Does anyone know the term for this? I had "Type Driven Development" in my head, but I don't know if that's a broadly used term for this. It's a step past normal "strong typing", but I've loved this concept for a while and I'd love to have a name to refer to it by so I can help refer others to it.

"newtype", or kind of (but not exactly) the opposite of "Primitive Obsession"

Re: Use Your Type System

#10

Post by arrowsmith »

pclowes wrote: post #3

I like this. Very much falls into the "make bad state unrepresentable". The issues I see with this approach is when developers stop at this first level of type implementation. Everything is a type and nothing works well together, tons of types seem to be subtle permutations of each other, things get hard to reason about etc. In systems like that I would actually rather be writing a weakly typed dynamic language like…

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 ''
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