`System`

Process-level I/O and runtime introspection. Always in scope — no import needed. This page covers the surface specific to Wrenlift; for the stock Wren System methods see wren.io.

Print & write

Method	What it does
`System.print(value)`	Print `value.toString` followed by a newline. Returns `value` for chaining.
`System.print`	Print a blank line.
`System.printAll(seq)`	Print every element of `seq`, joined into one line, then a newline.
`System.write(value)`	Print without a trailing newline.
`System.writeAll(seq)`	`write` over a sequence.

System.print("hello, world")
System.write("loading…")
System.print(1 + 2)            // 3

Clocks

Method	What it does
`System.clock`	Wall-clock seconds since the runtime started. Monotonic; for benchmarking, not for time-of-day.

var t = System.clock
expensive()
System.print((System.clock - t) * 1000)  // ms

For time-of-day, calendar work, or formatted timestamps, use @hatch:time. Keeps the core System surface small.

Garbage collection

Method	What it does
`System.gc()`	Trigger a GC cycle. Useful between batches in long-running scripts so short-lived allocations don't get promoted to the old gen.

// In a game loop:
_frame = _frame + 1
if (_frame % 30 == 0) System.gc()

Wrenlift's default GC is generational; you almost never need to call System.gc() manually. The hook is there for games and other steady-state loops where you want to enforce a known GC cadence.

Process

Process-level extras — environment variables, arguments, exit — live in @hatch:os, not on System. The split keeps embed-friendly scripts portable (the wasm runtime has no std::env; @hatch:os is host-only).