Stdlib: Io

The Io namespace provides human-in-the-loop interaction. All four functions route through a channel (terminal by default; Slack, email, or custom via interface).

io.ask — blocking input

Blocks the current handler until the user responds.

answer = io.ask("How should I respond to this?")
# answer: str

choice = io.ask("Pick a priority", options: [low, medium, high])
# choice: the enum

pick = io.ask("Approve deployment?", options: [yes, no], via: slack)

Returns: str for free text, or the enum type when options: is provided.

io.confirm — yes/no approval

approved = io.confirm("Send this reply?\n\n{draft_reply}")
if approved { email.send(draft_reply, to: email.from) }

# Via a specific channel
approved = io.confirm("Delete 50 files?", via: slack)

Returns: bool — true if approved, false otherwise.

io.notify — non-blocking message

io.notify("Email classified as critical")
io.notify("Weekly report ready", via: slack)

Does not wait for a response.

io.show — display structured data

io.show(email_summary)
io.show(table(results))
io.show(chart(metrics))

Formats structured data for the terminal or UI.

Channels

via: selects the channel. Default is terminal; the stdlib ships with slack and email channels, and additional channels can be installed by implementing the Channel interface.

io.notify("Deploy started", via: slack)

Why a library, not keywords

io.ask, io.confirm, io.notify, and io.show are ordinary stdlib functions (imported with use std/io) rather than reserved words. Treating them as regular functions keeps the grammar small and lets them compose with the rest of the language: they work inside pipelines, accept lambdas for formatting, and can be wrapped by user code without fighting the parser. See The Standard Library.