{"id":"language--collection-for","name":"Collection loops, indexes, reverse, and where","owner":"yeho","package":"language","kind":"language","signature":"for item in collection { ... }\nfor item at i in collection { ... }\nfor item at i = 1 in reverse collection where condition { ... }\nfor key to value in map { ... }","description":"for can iterate collection values, expose an index, start that index elsewhere, reverse the traversal, or filter with where.","context":"Use collection iteration when you care about elements rather than storage positions.","parameters":[],"returns":"","members":[],"tags":["at","complete-program","cpu","for","in","language","loops","reverse","to","where","yeho"],"updated":"2026-09-09","source":{"repository":"yeho","path":"parser_loops.cpp; language-core.md §8.3"},"status":"stable","notes":["reverse appears after in and before the collection expression.","Map loops can bind key to value."],"examples":[{"id":"complete","title":"List runtime","description":"Use collection iteration when you care about elements rather than storage positions.","code":"list of int values = [2, 4]\nvalues.Add(6)\nvalues[1] = values[1] + 1\n\nint total = 0\nfor value in values\n{\n    total = total + value\n}\n\nConsole.Log(Text.Format(\"{0}:{1}:{2}\", Text.From(values.count), Text.From(values[1]), Text.From(total)))\n\nvalues.Clear()\nvalues.Add(9)\nvalues.Add(11)\nConsole.Log(Text.Format(\"clear:{0}:{1}:{2}\", Text.From(values.count), Text.From(values[0]), Text.From(values[1])))\n\n\n","manifest":"package = \"tests.compiler.kyber.listRuntime\"\nversion = \"0.1.0\"\nbackend = \"kyber\"\nosTarget = \"windows\"\narchTarget = \"x64\"\nselfContainedApp = false\n\n\n\n","tags":["cpu","complete-program"],"verification":"type checked","run":"cpu-oracle","source":"tests/compiler/kyber/list-runtime/start.yh","sha256":"efed7718e01407abb7d694c4b41c02b48cfe2dc69732025b1748ec79758472fa","checked":"2026-09-09","diagnostic":"","observedOutput":null,"checkedBackend":null}],"searchTerms":[],"url":"https://demonhunterlabs.com/academy/api?item=language--collection-for","json":"https://demonhunterlabs.com/reference/items/language--collection-for.json","markdown":"https://demonhunterlabs.com/reference/text/language--collection-for.md"}