std/tw

1 export, from std/tw.vyrn.

Theme-derived utility classes as a checked type. tw(theme) reads a flat theme.json at generation time and returns a module with TwClass (one class; finite, so the LSP completes it), Tw (space-separated classes), cls(c: Tw) -> Attr, and css() -> String, the baked stylesheet. A literal passed to cls is checked against Tw at compile time.

import { tw } from "std/tw"
import * as theme from tw("./theme.json")

theme.json:

{
  "colors":      { "brand": { "500": "#4f46e5" }, "white": "#ffffff" },
  "spacing":     { "0": "0", "1": "0.25rem" },
  "radius":      { "DEFAULT": "0.5rem", "full": "9999px" },
  "fontSize":    { "sm": "0.875rem" },
  "breakpoints": { "sm": "640px", "md": "768px" },
  "safelist":    ["book-card"]
}

radius.DEFAULT drives the bare rounded. Safelisted names join the type but get no CSS rule. An unknown top-level key, a non-string leaf, an unsafe class name or an unsafe CSS value fails generation, naming the offender.

Dependencies

The import graph shows the whole library.

Imports: scan json jsonread strings arrays strpred diag
Imported by: no other std module

tw fn

gen fn tw(theme: String) -> String

Reads the flat theme.json and returns the typed module. A malformed theme fails the load with a report naming the offending key.

Tests

20 test blocks in std/tw.vyrn. CI runs all of them.

Test names

twParseTheme flattens nested keys with dots
twParseTheme rejects a non-string leaf
a scalar directly under a top-level family is refused, not silently ignored
twAxisOf dashes color shade paths and keeps theme order
a theme that cannot be read is its own diagnostic, not a parse error
twClassSafe accepts utility names and rejects unsafe segments
twBuildVocab emits families in the locked order
twBoxDecl expands the shorthand sides
twRoundedClasses maps DEFAULT to bare rounded
twRuleFlat escapes the colon in a variant selector
twBuildCss is deterministic and puts media queries last
twTokenRegex factors the prefixes over the base alternation
safelist folds names into the token grammar after the derived vocabulary
safelist rejects a name that is not CSS-safe
safelist is a recognised top-level key (not an unknown-key error)
twUnknownKeyErrors names an unrecognised top-level key
twValueSafe accepts hex/length/ident and rejects injection
twCssValueSafe routes values through the std/scan single-token gate
twUnsafeValueErrors names a CSS-injecting leaf value by key
twUnsafeBreakpointErrors names a forging breakpoint key

Examples

4 programs in examples/ import this module. Each runs as WebAssembly and as a native binary.