std.env

The program's arguments and environment, as it was started. Linux keeps both under /proc/self exactly as the kernel passed them, so reading them needs no start-up code and works from any module. Cost: each call reads one small file into a Vec it returns; a program reads its arguments once.

// Every argument, the program's own path first, in `text` with the NUL each ends in. Argument i is text[begin(a,
// i)..end(a, i)], and text[end(a, i)] is its NUL, for a call into C that wants one.
pub struct Args { text:Vec[u8]; ends:Vec[usize]; }

// effects: alloc, diverge, ffi:__errno_location, ffi:close, ffi:lseek, ffi:open, ffi:read, ffi_precondition, free, io,
// local_read, local_write, mmio, stack_storage, trap, zero_init
pub fn args() -> std.core.Result[std.env.Args, std.io.IoError]

pub fn count(a:ro<std.env.Args>) -> usize  // effects: read:a

// Where argument i starts and ends in a.text; an i past the last argument is a guard failure.
pub fn begin(a:ro<std.env.Args>, i:usize) -> usize  // effects: read:a, trap

pub fn end(a:ro<std.env.Args>, i:usize) -> usize  // effects: read:a, trap

// The value of the variable called `name` when the program started, or None.
// effects: alloc, diverge, ffi:__errno_location, ffi:close, ffi:lseek, ffi:open, ffi:read, ffi_precondition, free, io,
// local_read, local_write, mmio, read:name, stack_storage, trap, zero_init
pub fn var(n:usize, name:ro<u8>[n]@host) -> std.core.Result[std.core.Option[std.vec.Vec[u8]], std.io.IoError]

A generic function's effects are what it may do for any arguments within its bounds, besides what their own trait members do.