René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"allow type parameters on type arguments","articleBody":"``` typescript\ninterface Map\u003ca\u003e {\n   [key: string]: a;\n}\n\n// IMPORTANT: here my intention is that the `read` and `run` methods are agreed on using the same type parameter\ninterface Command\u003cOptions\u003e {\n   read(args: string[]): Options;\n   run(options: Options): void;\n};\n\ninterface CopyCommandOptions {\n   from: string;\n   to:  string;\n}\n\ninterface CleanCommandOptions {\n   directory: string;\n   pattern: string;\n}\n\n\n// currently in TypeScript there are 2 options to to declare `knownCommands` below:\n// - Map\u003cCommand\u003cany\u003e\u003e which contaminates my code with `any`\n// - Map\u003cCommand\u003cCopyCommandOptions | CleanCommandOptions\u003e\u003e which has different semantics\n// ideally I wish I could declare it like this:\nlet knownCommands : Map\u003c\u003ca\u003eCommand\u003ca\u003e\u003e = { // \u003c-- hypothetical syntax\n    'copy': \u003cCommand\u003cCopyCommandOptions\u003e\u003e undefined,\n    'clean': \u003cCommand\u003cCleanCommandOptions\u003e\u003e undefined\n};\n\n// so that later I could the following do in a type safe manner:\nlet command = knownCommands[name];\ncommand.run(command.read(args));\n```\n","author":{"url":"https://github.com/zpdDG4gta8XKpMCd","@type":"Person","name":"zpdDG4gta8XKpMCd"},"datePublished":"2015-12-06T19:25:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/5959/TypeScript/issues/5959"}