# Writing GEML — one-page cheatsheet GEML is plain text. Every structured thing is one **typed block**: ``` === {#id .class key=val} === ``` The opening fence is **≥ 3** `=`. The **closing fence must be the same length**. To nest a block inside a block, make the **outer fence longer**: ``` ==== note Example code: === code {lang=python} print("hi") === ==== ``` **Easier — close by name.** Give a block an `#id` and close it with `=== #id`. That closes by *name*, not by length, so you can nest with all `===` fences and never miscount: ``` === note {#ex} Example code: === code {#snippet lang=python} print("hi") === #snippet === #ex ``` Body modes: `code` / `diagram` / `math` / `table` / `embed` are **raw**; `note` are **parsed prose**; `meta` is one `key=val` per line. ## Metadata ``` === meta title = "My doc" version = 0.1 === ``` In prose, `{{title}}` inserts a meta value (an unknown key is a build **error**). ## Headings & lists (ATX only) ``` # Title ## Section {#explicit-id} - bullet 1. ordered - nested by indentation (2 spaces) - [ ] task - [x] done ``` ## Inline `*em*` `**strong**` `` `code` `` `~~strike~~` `$a^2$` (inline math) `[text](https://x)` `[text](#id)` `[[#id]]` (auto text) `[^note]` `![alt](pic.png)` A reference to a missing id is a build **error**. Define a footnote with `[^note]: text` on its own line, then cite it inline with `[^note]`. ## Tables ``` === table {#fy caption="Sales" format=csv header=1 compute="FY [%.1f] = Q1 + Q2 + Q3 + Q4" summary="Seg = 'Total'; Q1 = sum(Q1); FY = sum(FY)"} Seg, Q1, Q2, Q3, Q4 Cloud, 1, 2, 3, 4 === ``` - The attribute object `{…}` is **one physical line** (don't wrap it). - `compute`: `Name = expr` over `+ - * / ( )`, columns by header name (quote names with spaces: `'Unit Price'`) or letter `A,B,…`; `;`-separate multiple formulas; `[%.1f]` sets number display. - `summary`: one foot row; each cell is a literal (`'Total'`) or an aggregate expression over `sum/avg/min/max/count`. A bare (non-aggregated) column is an **error**. - Visual form also works: `| a | b |` rows with a `|---|` separator. ## Diagrams & charts ``` === diagram {#flow format=mermaid caption="Flow"} graph LR A --> B === ``` Chart drawn from a table (empty body — the spec is in the attributes): ``` === diagram {format=geml-chart data=#fy type=bar x=Seg y=FY} === ``` `type` ∈ `bar|line|area|pie|scatter`; `x`/`y` are column names; `data=#id` must point at a table; a typo'd column or dangling id is a build **error**. ## Math ``` === math {#g caption="Gaussian"} \int_{-\infty}^{\infty} e^{-x^2} dx = \sqrt{\pi} === ``` ## Things that are build ERRORS — avoid them - A reference / footnote / chart column / `{{meta}}` key that does not resolve. - A duplicate `#id`. - A block not closed by an **equal-length** fence (when nesting, the **outer** fence must be longer than any fence inside it). - A `summary` cell using a column that isn't wrapped in an aggregate. - Raw HTML (there is none in GEML).