Function boxSide

test/compute-engine/fungrim-loops.test.ts:165–181

(side: MathJSON, types: Record<string, string>)

    }

    const boxSide = (side: MathJSON, types: Record<string, string>): string => {
      ce.pushScope();
      try {
        for (const w of collectWildcards(side)) {
          try {
            ce.declare(w, types[w] ?? 'complex');
          } catch {
            /* tolerate */
          }
        }
        const b = ce.box(side as never);
        expect(b.isValid).toBe(true);
        return JSON.stringify(b.json);
      } finally {
        ce.popScope();
      }
    };

    /** Join two canonical sides, renaming wildcards jointly by order of
     *  first appearance — so `f(_a,_b) → g(_b)` and `f(_x,_y) → g(_y)` get