18 replies

Improving `Array.isArray` for More Precise Type Narrowing

can

Array.isArray

Array.isArray

Array.isArray

Array.isArray be improved to work better to narrow array types, or is there an alternative?
like this is horrible

import { Array } from "effect"
interface IntradayData { something: number } 

declare const _ = _: IntradayData | readonly IntradayData[] | null
Array.isArray(_) ? _[0] as IntradayData | undefined ?? null : _ as IntradayData

import { Array } from "effect"
interface IntradayData { something: number } 

declare const _ = _: IntradayData | readonly IntradayData[] | null
Array.isArray(_) ? _[0] as IntradayData | undefined ?? null : _ as IntradayData

import { Array } from "effect"
interface IntradayData { something: number } 

declare const _ = _: IntradayData | readonly IntradayData[] | null
Array.isArray(_) ? _[0] as IntradayData | undefined ?? null : _ as IntradayData

import { Array } from "effect"
interface IntradayData { something: number } 

declare const _ = _: IntradayData | readonly IntradayData[] | null
Array.isArray(_) ? _[0] as IntradayData | undefined ?? null : _ as IntradayData

the original Array.isArray improved this, but ended up with

any

any

Improving `Array.isArray` for More Precise Type Narrowing

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