tsvsheet.go — A spreadsheet for plain text — a .tsvt file is the spreadsheet.

A spreadsheet for plain text. A .tsvt file is the spreadsheet — a single TAB-separated grid whose cells are literal values or =formulas that address other cells in A1 notation (B2, D2:D5), computed in place, versioned as text, diffed line by line.

Playground

Open the playground → — the real engine, compiled to WebAssembly, running entirely in your browser. No server, no upload: edit any cell (a value or an =formula), watch it recompute live, toggle the .tsvt source pane, and copy the result to your clipboard. Wrap TODAY(), NOW(), ISNOW() (or RAND(), TICK()) in volatile() and they tick against your own clock.

Model

A .tsvt is the whole spreadsheet — one grid of cells, each either a literal value or an =formula. Formulas address other cells in A1 notation: a single cell (B2), a range (D2:D5), or a cross-sheet reference ("prices"!A1). Cells are computed in dependency order; a bad reference propagates #REF!, a cycle propagates #CIRC!. Because the file is plain TSV, it versions as text and diffs line by line.

The formula expression sublanguage is Excel-faithful: ^ (power), & (concat), postfix %, TRUE/FALSE, and error-value literals over A1 cell and range references — plus one unix-native addition, the pipe operator. The grid itself is plain TSV split by the host — only the =formula cells are parsed.

Pipes

Formulas compose like a shell pipeline. expr | fn(arg, …) feeds the expression in as the function’s first argument, so a multi-stage transformation reads left to right in execution order instead of inside-out:

=A2:A10 | sort() | unique() | count()     ≡  =count(unique(sort(A2:A10)))
=avg(B2:B7) | round(1) | concat(" avg")   ≡  =concat(round(avg(B2:B7), 1), " avg")
=A1 | round(2)                            ≡  =round(A1, 2)
=A1 & B1 | len()                          ≡  =len(A1 & B1)    (pipe binds loosest)

The pipe is pure sugar over function calls — the two spellings are the same formula, chains fold left, and error values flow through stages exactly as they do through arguments. There is no new execution model: the processor normalizes a pipe to its composed call when it parses the formula, and everything downstream (dependency order, memoization, explain, structural edits) sees an ordinary call — while your sheet keeps the spelling you wrote. Specified in SPECIFICATION.md §5.4.

Command line

The tsvsheet CLI renders, parses, checks, and explains sheets, serves a browser editor, or opens a bubbletea TUI — one shared engine behind all of them, with unix stdin/stdout discipline:

tsv render sheet.tsvt          # compute and print the grid
tsv check  sheet.tsvt          # validate formulas and references
tsv explain D5 < sheet.tsvt    # trace how a cell was produced
tsv serve  sheet.tsvt          # local browser editor (reads/writes the file)
tsv tui    sheet.tsvt          # terminal editor

A .tsvt can carry a #! shebang and # comments, so a sheet is directly executable — render is the default command.

Examples

Everything below runs today, with the shipped engine and nothing else — each example was computed with tsv render exactly as shown.

Bars in the grid

rept scaled by max turns a column into a chart you can cat, diff, and review — the poor man’s sparkline, entirely inside the language:

Month	Revenue	Chart
Jan	1200	=rept("█", round(B2/max($B$2:$B$4)*20, 0))
Feb	1350	=rept("█", round(B3/max($B$2:$B$4)*20, 0))
Mar	1810	=rept("█", round(B4/max($B$2:$B$4)*20, 0))

Month	Revenue	Chart
Jan	1200	█████████████
Feb	1350	███████████████
Mar	1810	████████████████████

Shares that reflow

A percentage column over sum recomputes every share when any one number changes — the grid stays honest without a spreadsheet application in sight:

Category	Monthly	Share %
Compute	4200	=round(B2/sum($B$2:$B$4)*100, 1)
Storage	1900	=round(B3/sum($B$2:$B$4)*100, 1)
Network	1100	=round(B4/sum($B$2:$B$4)*100, 1)

A chart that is a sheet

Cells compute text — including SVG. A sheet with input/output is a function (SPECIFICATION.md §8), so a bar chart can be written in tsvsheet and embedded from any other sheet. bar-chart.tsvt scales its bars with max, assembles <rect> fragments with concat, and outputs one complete SVG document:

label	value	h	svg fragment
=input(1)	=input(2)	=round(B2/max($B$2:$B$5)*100, 0)	=concat("<rect x='20' y='", 120-C2, "' width='60' height='", C2, "' fill='#4C78A8'/>")
…	…	…	…
=output(concat("<svg xmlns='http://www.w3.org/2000/svg' width='325' height='145'>", D2, D3, D4, D5, "</svg>"))

Any report embeds it as an ordinary formula, and extracting the computed cell yields a rendered chart:

Quarter	Revenue
Q1	120
Q2	180
Chart	=sheet("bar-chart.tsvt", A2, B2, A3, B3, …)

tsv render report.tsvt | awk -F'\t' '$1=="Chart"{print $2}' > chart.svg

The chart is a sheet: parameterized, versioned, diffable, forkable. A chart library is a directory of .tsvt files.

Emitting other text languages

The same trick targets any text-based tool. An edge-list sheet whose third column assembles Graphviz statements becomes a rendered dependency diagram in one pipeline:

service	depends-on	dot
api	db	=concat("  ", A2, " -> ", B2, ";")
api	cache	=concat("  ", A3, " -> ", B3, ";")
web	api	=concat("  ", A4, " -> ", B4, ";")

{ echo 'digraph deps {'; tsv render edges.tsvt | cut -f3 | tail -n +2; echo '}'; } | dot -Tsvg -o deps.svg

(String literals have no escape sequences — for a literal " inside emitted text, use char(34).)

Plotting computed output

The computed grid is plain TSV — the native input of the standard plotting toolchain. Feed it to gnuplot from a pipeline, or to d3 directly — d3.tsv() parses render output as-is:

tsv render sales.tsvt > sales.tsv         # then: plot 'sales.tsv' with linespoints
const rows = await d3.tsv("sales.tsv", d3.autoType);

Formulas stay in the source, computation stays in the engine, and every downstream tool sees exactly what a spreadsheet export would have given it — minus the spreadsheet.