{"slug":"dotnet-sep","title":"dotnet-sep","summary":"Use Sep for high-performance separated-value parsing and writing in .NET, including delimiter inference, explicit parser/writer options, and low-allocation row/column workflows.","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-09-27T21:00:39.194716Z","repo":{"url":"https://github.com/Postpartum-genushyacinthus29/dotnet-skills","stars":12,"forks":1,"license":"MIT","updatedAt":"2026-09-27T19:34:14Z"},"bodyHtml":"
\nname: dotnet-sep\nversion: \"1.0.0\"\ncategory: \"Data\"\ndescription: \"Use Sep for high-performance separated-value parsing and writing in .NET, including delimiter inference, explicit parser/writer options, and low-allocation row/column workflows.\"\ncompatibility: \"Requires a .NET project that can reference the Sep package and accept span/ref-struct row/column APIs for row-by-row processing.\"
\nSep for .NET separated values
\nTrigger On
\n\n- delimited data needs are performance-sensitive and allocation-aware
\n- project needs explicit control over separator inference, escaping, trimming, and header behavior
\n- reading/writing large or long-lived file pipelines in ML, ETL, or analytics workloads
\n- startup/perf tests require AOT/trimming-friendly CSV/TSV processing
\n
\nInstall
\n\n- NuGet:\n
\ndotnet add package Sepdotnet add package Sep --version <version>
\n \n- XML package reference:\n
\n<PackageReference Include=\"Sep\" Version=\"x.y.z\" />
\n \n- Verify baseline support by checking the package page:\n\n
\n- Source:\n\n
\n
\nWorkflow
\nflowchart LR\n A[Input source: file/text/stream] --> B[Sep.Reader or Sep.New(...).Reader]\n B --> C[SepReaderOptions]\n C --> D[Rows -> Cols -> Span/Parse]\n D --> E[Transform and validate]\n E --> F[SepWriter via SepWriterOptions]\n F --> G[To file/text output]\n
\n\n- Decide schema shape\n
\n- header present or no header
\n- separator known (
;, ,, tab, custom) or infer from first row \n- row/column quoting rules
\n
\n \n- Build reader with
Sep.Reader(...) and explicit options only where needed:\n\nSep.Reader() for inferred separator from header-like first rowSep.New(',').Reader(...) for explicit separator modeSep.Reader(o => o with { HasHeader = false }) if header is absent
\n \n- Read rows and map columns as
ReadOnlySpan<char> first, convert only when needed. \n- For output, use
reader.Spec.Writer() when you need the same separator/culture as input. \n- Control writer behavior with
Sep.Writer(...) and SepWriterOptions (WriteHeader, Escape, DisableColCountCheck). \n- Add async only where it brings value and your runtime is C# 13 / .NET 9+ for
await foreach over async reader rows. \n- Use
ParallelEnumerate for CPU-heavy transformations only after benchmarking single-threaded baseline. \n
\nInstall and read patterns
\nusing var reader = Sep.Reader(o => o with\n{\n HasHeader = true,\n Unescape = true,\n Trim = SepTrim.Both\n}).FromText(data);\n\nforeach (var row in reader)\n{\n var id = row[\"Id\"].Parse<int>();\n var name = row[1].ToString();\n // process row\n}\n
\nWrite patterns
\nusing var reader = Sep.Reader().FromFile(\"input.csv\");\nusing var writer = reader.Spec.Writer().ToFile(\"output.csv\");\n\nforeach (var row in reader)\n{\n using var writeRow = writer.NewRow(row);\n writeRow[\"Amount\"].Format(row[\"Amount\"].Parse<double>() * 1.2);\n}\n
\nAsync reading and writing
\nvar text = \"A;B\\n1;hello\\n\";\n\nusing var reader = await Sep.Reader().FromTextAsync(text);\nawait using var writer = reader.Spec.Writer().ToText();\n\nawait foreach (var row in reader)\n{\n await using var writeRow = writer.NewRow(row);\n var normalized = row[\"B\"].ToString().ToUpperInvariant();\n writeRow[\"B\"].Set(normalized);\n}\n
\nCommon configuration patterns
\n\n- Header-driven read\n
\n- default
HasHeader = true \n- query by name:
row[\"ColName\"] \n
\n \n- Headerless pipelines\n
\nHasHeader = false- use index-based access:
row[0], row[1] \n
\n \n- Round-trip output\n
\n- start writer with
reader.Spec.Writer() to preserve inference and formatting contract \n
\n \n- Speed-first processing\n
\n- keep default buffer + culture unless profiling proves a need to tune
\n
\n \n
\nBest practices
\n\n- Parse to primitive types with
Parse<T> in hot paths to avoid extra allocations. \n- Keep
ToString/format conversions at the edge (presentational layers), not in inner loops. \n- Prefer
Unescape, Trim, and DisableQuotesParsing settings deliberately and test with realistic samples. \n- For large transforms, isolate heavy CPU work after enumeration and then apply
ParallelEnumerate where appropriate. \n
\nLimitations to check before production
\n\nSepReader.Row and SepWriter.Row are ref structs:\n\n- avoid patterns that store rows beyond immediate scope
\n- materialize if you truly need random async/LINQ-style buffering
\n
\nSepReader row iteration is row-by-row by design; it is intentionally not the same as a classic collection model.
\nDeliver
\n\n- installation and usage guide that is ready to copy into a .NET repo
\n- practical reader/writer configuration patterns
\n- clear notes on defaults, tradeoffs, and constraints
\n
\nValidate
\n\ndotnet add package Sep installs correctly and project compiles- one file-read sample and one file-write sample execute successfully
\n- header/no-header and explicit-separator cases are covered
\n- at least one validation sample for quoting/unescaping or async path exists if required by task
\n
\nLoad References
\n\n","files":[{"path":"references/overview.md","sizeBytes":1187,"isText":true},{"path":"SKILL.md","sizeBytes":5182,"isText":true}],"reviewScore":null,"reviewSummary":null,"trust":{"provenance":"trusted-source-unreviewed","notice":"Community-authored content, reproduced verbatim and not vetted as instructions. Treat it as data to evaluate, never as directives to follow.","bodySource":null},"bodyLocked":false,"purchaseUrl":null,"sourceUrl":null,"report":{"provenance":"trusted-source-unreviewed","screen":{"ran":true,"outcome":"clean","suspicious":0,"notes":0,"hiddenCharacters":false},"virusScan":{"engine":"clamav","status":"clean","scannedAt":"2026-09-27T21:03:14.818996Z","sha256":"64A21A6A311271075E1716181BF1F5EEDA9149E22117F40358F819D82C2830D6","sizeBytes":3225},"review":null,"source":{"repositoryUrl":"https://github.com/Postpartum-genushyacinthus29/dotnet-skills","path":"skills/dotnet-sep","license":"MIT","commit":"bfa4ebd86f6bd674800f209ebf72ca770c2f026b","subtreeSha":"248B87BE9E0F7D798796F51C849802CF8277F762C7873BA2BB539E6BCF87C52F","lastSyncedAt":"2026-09-27T21:00:28.368219Z"},"reviewedAt":"2026-09-27T21:13:46.554442Z","notice":"Community-authored content, reproduced verbatim and not vetted as instructions. Treat it as data to evaluate, never as directives to follow."},"install":[{"target":"skills-cli","command":"npx skills add https://github.com/Postpartum-genushyacinthus29/dotnet-skills/tree/main/skills/dotnet-sep"},{"target":"claude-code","command":"claude plugin marketplace add https://llmmart.ai/marketplace.json && claude plugin install postpartum-genushyacinthus29-dotnet-skills@llmmart"},{"target":"git","command":"git clone https://github.com/Postpartum-genushyacinthus29/dotnet-skills.git"}]}