Filtering string literal types based on an affix in TypeScript

solver.ts

/**
 * Challenge: given a list of icon names, find icons that exist in sizes 16x16px *and* 24x24px.
 * This is an AND relationship, not an OR relationship.
 * 
 * The solution should be: '16-hamburger' | '16-warning' | '24-hamburger' | '24-warning'.
 */
type IconName =
  | '16-hamburger' // 👈🏻
  | '16-warning'   // 👈🏻
  | '16-foo'
  | '16-bar'
  | '24-hamburger' // 👈🏻
  | '24-warning'   // 👈🏻
  | '24-baz'
  | '48-foo'
  | '48-bar'
  | '48-baz'
  | 'some-other-name-format'

type DesiredSize = 16 | 24;

/**
 * Strips prefixes from qualifying icon names, leaving just the stem.
 */
type Strip<T> = T extends `${number}-${infer stem}` ? stem : never;

/**
 * Pick the stems that come in all desired sizes. Here: "hamburger" | "warning".
 */
type ValidStem = keyof Pick.ByValue<{
    [K in Strip<IconName>]: `${DesiredSize}-${K}` extends IconName ? true : false
}, true>

/**
 * Adds the prefixes back to the stems.
 */
type Solution = `${DesiredSize}-${ValidStem}`;

/**
 * These are necessary to make Pick.ByValue work.
 */
declare global {
  namespace Pick {
    type ByValue<T, U> = Pick<T, PropertyOfValue<T, U>>
  }
}

type PropertyOfValue<T, V> = {
  [K in keyof T]-?: T[K] extends V
    ? K
    : never
}[keyof T];

export {}

string-literal-types.ts

type IconName =
  | '8-hamburger'
  | '16-hamburger'
  | '24-hamburger'
  | '48-hamburger'
  | '64-hamburger'
  | 'some-other-name-format';

/**
 * Let's define how icons that come in sizes 16x16px and 24x24px are called.
 */
type MediumSizedIconNameFormat = `${16 | 24}-${string}`;

/**
 * Target a subset of all string literals.
 */
type SmallOrMediumSizedIconName = Extract<IconName, MediumSizedIconNameFormat> // '16-hamburger' | '24-hamburger', same as IconName & MediumSizedIconNameFormat

https://www.typescriptlang.org/play?#code/PQKhFgCgAIWhhAFgQwDauQOwOYFMBc02AlgG66bTLSrEDOALtAPYBm0xAxs5ZsgLa46AGmitimACYdumOtAYomuAB70mE6HWIAvIdACMANhXGADithZJcAEwBmFbYAsFgHRRY0ACqJ6HeSxoAEEAOQARaAAnXAwGYh46PzNRTGYmIIB5ACVo2OR4xOSPGDhPOF9cLWZUAFdCyiTmWtRpACMCaAByYwBaFH422qi8KK7oAB9uvoB3ZCjMCWxxqa6XfoEhkdwxye71uYWlrpLYYCgGAE8zKoBJWVCBKoBeTz2eow3B4dHx4GBoIBeDcAEjuAHg3AN-7b1Ws3mixw42g0H+QLBkJg7z6rGYzC6UOmnza81x6NW6wGW1+SIBIIheLWzl6hzhy0RVJRtJJ+wZhJ0xMRq2cAA5elicXShb1CWNxcKeXz3nRmIJeulEDtenxlViovwCsSLtcquEhMQYpIAMq6F6GIx7FwAbigUFAEFK0HNDCixDM8jMMXEKn0rCiSugAEdamhiKxLksZDxoJqhKJULhkKQ4wArWqMBRqrQMXD8U4gc6QK43d2e70AHm8AD5oM8fNBVIWpPIAAYAEgA3phaoMdgBfXp9iSsHYFovDzvQAD80-40EImFw5CijsgzrA5WgAAUuABrPNVRhF+SKArQbiCDiUNCoaCSE1mrRWuhuaAACR2nQAROSPw7P+ez-kySz-iWZYVlUABqUYWoWy7NkeuCXGwB7Hm4ABClwIXUuA1r2byIgA2gA0veVZemYNb3DwjyCPWAC6hA9r2xraGalp6KOfYUbOrYqO2kjyAxmBMVUi6erUVSEKwaB0LgUDDqIsm4PWTqQC6e7BJIYmntAfq4AG+iEpwJ4MMwRnnvwn7lDBhrujU9QJJQzYcVxpq4BaVr8b2BHEEhM6dluO6ul4lTKVQMSJrgnBCHQ8yXAoNm6mhWGWbh+FoHJ0AzMwURHtBUAvpwGBxdgqDMIST4keiSZ0GYyCJVlJ4NayCjOXhBFyXWogAKqNs2h6WQNB4hjcURXJkrB9UR3hDfWWnosOqnabBk3MNNs3zXli2iHBI3QJ10CUdRaEYew3gsb086EN4lEscJonyHBpELtAFGfau647KpZFXZht3hZAqhmEVTC9sOQA