Function paramsOf

scripts/fungrim/load.ts:234–246

(head: string)

 * declared `function`, and this wins over any Element conjunct. The engine
 * (strict mode) reports `expected-function` when a symbol declared with a
 * non-function type is applied, so declaring such a variable `complex` makes
 * the whole entry fail Stage 1. A `DirichletGroup` membership, for example,
 * falls through `inferType` to `complex`, yet `chi` is a function.
 */
export function variableTypes(e: Entry): Record<string, string> {
  const types: Record<string, string> = {};
  const applied = new Set<string>();
  const vars = new Set(e.variables);
  const walk = (x: unknown): void => {
    if (!Array.isArray(x)) return;
    if (typeof x[0] === 'string' && vars.has(x[0])) applied.add(x[0]);
    if (x[0] === 'Element' && typeof x[1] === 'string' && x.length >= 3)
      types[x[1]] ??= inferType(x[2]);
    for (const y of x) walk(y);
  };
  walk(e.assumptions);