json_schema.ts

type TypeOfSchema<T extends any> =
  T extends { type: "null" } ?
    null :
  T extends { type: "boolean" } ?
    boolean :
  T extends { type: "object" } ?
    { [K in keyof T["properties"]]: TypeOfSchema<T["properties"][K]> } :
  T extends { type: "array" } ?
    T extends { items: infer U } ?
      { foo: TypeOfSchema<U>[] } :
      [] :
  T extends { type: "number" } ?
    number :
  T extends { type: "string" } ?
    string :
  T extends { const: infer U } ?
    U :
  T extends { anyOf: (infer U)[] } ?
    { foo: TypeOfSchema<U> } :
    never


// "null", "boolean", "object", "array", "number", or "string"

const schema = {
  type: "object",
  properties: {
    foo: {
      type: "string" as "string"
    },
    bar: {
      const: "bar" as "bar"
    },
    biz: {
      type: "array" as "array",
      items: { type: "string" as "string" },
    },
    baz: {
      anyOf: [{ const: "bar" as "bar" }, { const: "baz" as "baz" }]
    }
  },
}
type Hop = TypeOfSchema<typeof schema>