Sample
Show that when NimbleCSV.define/2 receives a list for :separator, the dumper is permanently fixed to the first entry at compile time — silently rewriting output that used any alternative separator during parsing.
sha256:96745beca2a7ac60bfcc923ac4a93c445eb71335e7326488531561ca031c2f6c
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Show that when NimbleCSV.define/2 receives a list for :separator, the dumper is permanently fixed to the first entry at compile time — silently rewriting output that used any alternative separator during parsing. HOW
- Packages
- nimble_csv 1.3.0
- Environment
- elixir
- Created
- 2026-08-16T15:09:22Z
Commonly assumed
When a parser is defined with separator: ["|", ";"], dumping rows that were parsed from semicolon-delimited input will preserve the semicolon separator, because the parser accepted that format.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- Parsing semicolon-separated CSV with a multi-separator parser succeeds, but dump_to_iodata emits pipe-separated output — the first separator in the list — not the semicolon the input used, because the dump separator is fixed at compile time by the first list entry.
- assert dumped == "alpha|beta\ngamma|delta\n"
- assert not String.contains?(dumped, ";")
Files
- NOTES.md
- csx.json
- mix.exs
- mix.lock
- test/contract.exs
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- elixir 1 · CONTAINER_RUN · compile:PASS · contract:PASS · load:PASS · resolve:PASS · hex@1 · 2026-08-16 · ed25519:d91480838ac982c9