vercel-labs--zerolang/docs/articles/modules/env.md

When To Use std.env

In Zerolang, use std.env for hosted environment variable lookup and simple typed configuration values.

Runnable today:

API	Return	Notes
std.env.get(name)	Maybe<String>	Returns a hosted process environment value when present.
std.env.has(name)	Bool	Reports whether a hosted environment variable exists.
std.env.getOr(name, fallback)	String	Returns the environment value or a caller-provided fallback.
std.env.equals(name, expected)	Bool	Compares an environment value with expected text without exposing a missing value as success.
std.env.parseBool(name)	Maybe<Bool>	Parses an environment value as Bool.
std.env.parseBoolOr(name, fallback)	Bool	Parses a boolean environment value or returns a caller-provided fallback.
std.env.parseI32(name)	Maybe<i32>	Parses an environment value as i32.
std.env.parseI32Or(name, fallback)	i32	Parses an i32 environment value or returns a caller-provided fallback.
std.env.parseU32(name)	Maybe<u32>	Parses an environment value as u32.
std.env.parseU32Or(name, fallback)	u32	Parses a u32 environment value or returns a caller-provided fallback.
std.env.parseUsize(name)	Maybe<usize>	Parses an environment value as usize.
std.env.parseUsizeOr(name, fallback)	usize	Parses a usize environment value or returns a caller-provided fallback.

Current limits:

• Dotenv/source composition.
• Secret redaction metadata.
• Rich diagnostics for missing keys, invalid values, and source precedence.

Example

pub fn main(world: World) -> Void raises {
    let mode: String = std.env.getOr("ZERO_MODE", "default")
    let verbose: Bool = std.env.parseBoolOr("ZERO_VERBOSE", false)
    let delta: i32 = std.env.parseI32Or("ZERO_DELTA", 0)
    let limit: u32 = std.env.parseU32Or("ZERO_LIMIT", 10)
    let workers: usize = std.env.parseUsizeOr("ZERO_WORKERS", 1)
    if std.env.equals("ZERO_MODE", "debug") && verbose && delta >= 0 && limit > 0_u32 && workers > 0 {
        check world.out.write(mode)
        check world.out.write("\n")
    } else {
        check world.out.write("default\n")
    }
}

Design Notes

Environment access is a hosted capability. Non-host targets reject std.env unless they explicitly provide an environment capability.

Diagnostics name the selected target context.