René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Mapped tuple types don't infer as arrays in generics","articleBody":"**TypeScript Version:**  3.1.0-dev.20180802\r\n\r\n**Search Terms:**\r\n\r\nMapped tuple type generic infer array\r\n\r\n**Code**\r\n\r\n```ts\r\ntype Element\u003cT\u003e = T extends Array\u003cinfer U\u003e ? U : never;\r\ntype Mapped\u003cT\u003e = { [K in keyof T]: T[K] };\r\n\r\ntype F\u003cT\u003e = Element\u003cMapped\u003cT\u003e\u003e;\r\ntype R1 = F\u003c[string, number, boolean]\u003e; // never\r\ntype R2 = Element\u003cMapped\u003c[string, number, boolean]\u003e\u003e; // string | number | boolean\r\n```\r\n\r\n**Expected behavior:**\r\n\r\nThe type of `R1` should be `string | number | boolean`.\r\n\r\n**Actual behavior:**\r\n\r\nThe type of `R1` is `never`.","author":{"url":"https://github.com/jscheiny","@type":"Person","name":"jscheiny"},"datePublished":"2018-08-02T18:37:19.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/26163/TypeScript/issues/26163"}