Lexical Conventions

An Adam source file is tokenized as Rust/CEL tokens (via proc_macro2): identifiers, integer and float literals (with optional type suffixes), string literals, and punctuation, exactly as cel-parser’s own lexical grammar defines them. Adam adds exactly one lexical extension on top of CEL’s own conventions: doc comments.

Comments

// starts a line comment; /* ... */ a block comment — the same two forms C, Rust, and CEL all share:

// a whole-line comment
cell width: i32 = 1920; // a trailing comment
/* a block comment, on one line or several */

Doc comments

/// immediately before a cell, source, relationship, conditional, or out declaration, and //! immediately before the sheet keyword itself, are Adam’s own addition to CEL’s lexical grammar: doc comments, recovered by the language server and the formatter, and otherwise inert — they carry no meaning when the sheet resolves:

//! A sheet describing a simple resize dialog.
sheet image_resize {
    /// The image's width in pixels, before any resampling.
    cell width_pixels: i32 = 1920; // a trailing comment
    /* a block comment,
       on several lines */
    cell height_pixels: i32 = 1080;
}

Keywords and reserved identifiers

Keywords: sheet, cell, source, relationship, conditional, out, require, filter. None of these can be used as a cell or sheet name. _ is not a keyword but is reserved in two specific positions: a conditional’s default branch (_ => { ... }, the default branch and reverting to source section), and inside a filter expression (the candidate value, the filter grammar); elsewhere it is an ordinary identifier.

Punctuation

: (type annotation), = (cell initializer), := (binding/output body), => (conditional branch), ; (declaration terminator), , (list separator), { } (block delimiters), ( ) (tuple/grouping delimiters).