Jadpo is experimental and not ready for production. These docs follow the compiler's main branch as of 5 Nov 2026. What's built · Install 0.3.0

ReferenceErrors

Errors Logic · rule

`type.match_duplicate_pattern`

Match pattern is already covered.

Area 3, Logic; not declinable; the next step is usually the agent's.

example

function describe(state: DeliveryState) -> Label {    return match state {        DeliveryState.pending -> "Pending"        DeliveryState.pending -> "Waiting"        DeliveryState.sent -> "Sent"        DeliveryState.failed -> "Failed"    }}

jadpo checkcheck failed: 1 error, 2 files

error DeliveryState.pending is matched twice

--> main.jadpo:4:9

  |3 |         DeliveryState.pending -> "Pending"  |         --------------------- first matched here4 |         DeliveryState.pending -> "Waiting"  |         ^^^^^^^^^^^^^^^^^^^^^ matched again

reason: Each case is matched once; the first arm takes every value this one would, so this arm never runs.
next: Remove this arm, or merge its body into the first (agent)
rule: type.match_duplicate_pattern
help: https://jadpo.dev/docs/errors/type.match_duplicate_pattern

Markdown for agents: /docs/errors/type.match_duplicate_pattern.md.Built from Jadpo main at aee2e8f.