ENV
ENV is an immutable Map<String, String> snapshot of the process environment, taken once at startup. It supports all regular Map operations — get, has?, keys, count, each, etc.
Although the snapshot itself is immutable, the global ENV namespace is an ambient input. Reading it is foul because results can differ between process launches without appearing in a function's arguments.
module ENV
ENV : Map<String, String>
main receives the environment snapshot as its second parameter, which is the same immutable value exposed by global ENV. Reading the parameter is pure because the dependency is explicit in the function signature.
Examples
main(args, env) do
let level = env.get("LOG_LEVEL", "info")
IO.printLine("log level: ${level}")
endget
get(key, default)has?
has?(key)keys
keysvalues
valuescount
counteach
each(f)entries
entriesset
set(name, value)Sets a variable for THIS process and every child it starts. ENV is a snapshot, so it is rebuilt by the write — a later ENV.get answers what was set, not what the process started with.
This is how a program decides what a child sees: Kex.AST shells out to the compiler named by $KEX, so a tool that knows which compiler it means says so here rather than hoping PATH agrees.