{"id":"language--extension-functions","name":"Extension functions","owner":"yeho","package":"language","kind":"language","signature":"Function(Type extension value, ...) -> ReturnType\nvalue.Function(...)","description":"Mark the first parameter extension to let an ordinary function use readable value.Method(...) call syntax.","context":"Use an extension when behavior conceptually belongs beside a type but you do not own or should not expand the type declaration.","parameters":[],"returns":"","members":[],"tags":["cpu","extension","functions","language","yeho"],"updated":"2026-09-09","source":{"repository":"yeho","path":"tests/compiler/kyber/legalized-call-forms/start.yh; parser_types.cpp parseParameters"},"status":"stable","notes":["extension is a binding mode on the first parameter.","The direct function remains explicit and testable even though call syntax reads like a method."],"examples":[{"id":"complete","title":"Complete extension functions example","description":"Use an extension when behavior conceptually belongs beside a type but you do not own or should not expand the type declaration.","code":"thing Point\n{\n    int x\n    int y\n    Point(int x, int y) { this.x = x this.y = y }\n}\nMagnitude(Point extension value, int offset = 0) -> int\n{\n    return value.x + value.y + offset\n}\nPoint point = Point(1, 5)\nConsole.Log(Text.From(point.Magnitude(offset: 7)))\n","tags":["cpu","language"],"run":"cpu-oracle","expected":null,"verifyRun":false,"manifest":"manifestVersion = \"2\"\npackage = \"api.example.language__extension_functions\"\nversion = \"0.1.0\"\nlanguageEdition = \"yeho-core-2026.1\"\n\n[app]\nkind = \"headless\"\n","verification":"type checked","sha256":"99a6cb2088f0c3010191490bd25acef3b1bf92cfcd4b14e6b02441c44933ce0a","checked":"2026-09-09","diagnostic":"","observedOutput":null,"checkedBackend":null}],"searchTerms":[],"url":"https://demonhunterlabs.com/academy/api?item=language--extension-functions","json":"https://demonhunterlabs.com/reference/items/language--extension-functions.json","markdown":"https://demonhunterlabs.com/reference/text/language--extension-functions.md"}