string.integer.parse < 100

Here's an actual validator I'm trying to build

const decimals = type('string.integer.parse | number.integer < 28')

const decimals = type('string.integer.parse | number.integer < 28')

I want the input to be a number, potentialy in string form, and less than 28.

decimals("20") // passes fine
decimals(20) // passet file
decimals(100) // fails correctly
decimals("100") // passes *should fail*

decimals("20") // passes fine
decimals(20) // passet file
decimals(100) // fails correctly
decimals("100") // passes *should fail*

How do I build a check on the output of the parse?

26 Replies

ssalbdivad•4d ago

One of these will work:

const decimals = type("(string.integer.parse | number.integer) |> number < 28")

const decimals2 = type("string.integer.parse | number.integer").to(
    "number < 28"
)

const decimals = type("(string.integer.parse | number.integer) |> number < 28")

const decimals2 = type("string.integer.parse | number.integer").to(
    "number < 28"
)

McKamykOP•4d ago

yea I just discovered the .to method I like the idea of "one-shotting" it like in the first example, but feels like .to is a bit cleaner

ssalbdivad•4d ago

Yeah makes the grouping explicit without needing parens I think |> is better when it's not mixed with unions

McKamykOP•4d ago

what if its also nullable

type("null | string.integer.parse | number.integer").to("null | number < 28")

type("null | (string.integer.parse | number.integer) |> null | number < 28")

type("null | string.integer.parse | number.integer").to("null | number < 28")

type("null | (string.integer.parse | number.integer) |> null | number < 28")

Seems like with null its just way easier with .to

ssalbdivad•4d ago

Don't group the null in with the pipe that is confusing haha

type("string.integer.parse | number.integer").to(
    "number < 28"
).or("null")

type("string.integer.parse | number.integer").to(
    "number < 28"
).or("null")

McKamykOP•4d ago

oooooooo beginning to feel like zod lmao with the chaining

ssalbdivad•4d ago

Sometimes chaining is the easiest way to do something

McKamykOP•4d ago

yea

ssalbdivad•4d ago

Still tbh that doesn't look that much like Zod 😛

McKamykOP•4d ago

after. converting an internal api, and currently a public api from zod to arktype, arktype is 200x more legible completely ignoring the performance of it, its just much nicer already super duper impressed on the "typesafety" on the strings, that blows me away how thats even possible

ssalbdivad•4d ago

Yeah TS strings are very impressive. Especially that they can be that precise and that fast!

McKamykOP•4d ago

finding myself reaching for

const posInt = type("number.integer > 0")
const decimals = type("string.integer.parse | number.integer").pipe(posInt).pipe('number < 23')

const posInt = type("number.integer > 0")
const decimals = type("string.integer.parse | number.integer").pipe(posInt).pipe('number < 23')

very nice sorry dont mean to bother just having fun now

ssalbdivad•4d ago

I'd probably do .to("0 < number.integer < 23")

McKamykOP•4d ago

oh that second pipe should be to wait they should both be to?

ssalbdivad•4d ago

Well you can still abstract it out, but may as well validate the entire range at once? or they all have different max values

McKamykOP•4d ago

different max values but all positive

ssalbdivad•4d ago

to and pipe are same thing but to can parse a type def while pipe accepts a Type instance or a morph

McKamykOP•4d ago

I see

ssalbdivad•4d ago

I was going to say neater to have all the output validation occur at once rather than introducing more sequentiality with two pipes, but internally it will just be reduced to a single range anyways so doesn't really matter

McKamykOP•4d ago

y'all merge the .to's where you can?

ssalbdivad•4d ago

Yeah everything in the type system is fully reduced + normalized so if you pipe between two types with no transforms, it's just an intersection

McKamykOP•4d ago

aight ima get back to work my heads going to explode if I continue to ask questions lmao this is incredible

ssalbdivad•4d ago

Reductions like that are the coolest part of ArkType IMO GLHF!

McKamykOP•4d ago

last thing i'll say, I'm using neovim and was worried about not having an extension that gives me hints on the type def strings, but was happily surprised its carried by TS

ssalbdivad•4d ago

Yeah it was always TS-first with the extension just adding highlighting and error extraction. Would love to get support for other editors though if you're interested in translating the textmate rules.... LLMs must be pretty good at that kind of thing?

McKamykOP•4d ago

it would be my first foray into that level of neovim, when I get a chance I may look into it no promises 😂

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