\[\frac{x \cdot y + z \cdot \left(t - a\right)}{y + z \cdot \left(b - y\right)}\]
\frac{x \cdot y + z \cdot \left(t - a\right)}{y + z \cdot \left(b - y\right)}
double f(double x, double y, double z, double t, double a, double b) {
        double r8870 = x;
        double r8871 = y;
        double r8872 = r8870 * r8871;
        double r8873 = z;
        double r8874 = t;
        double r8875 = a;
        double r8876 = r8874 - r8875;
        double r8877 = r8873 * r8876;
        double r8878 = r8872 + r8877;
        double r8879 = b;
        double r8880 = r8879 - r8871;
        double r8881 = r8873 * r8880;
        double r8882 = r8871 + r8881;
        double r8883 = r8878 / r8882;
        return r8883;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019179 
(FPCore (x y z t a b)
  :name "Development.Shake.Progress:decay from shake-0.15.5"

  :herbie-target
  (- (/ (+ (* z t) (* y x)) (+ y (* z (- b y)))) (/ a (+ (- b y) (/ y z))))

  (/ (+ (* x y) (* z (- t a))) (+ y (* z (- b y)))))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0LC
loop/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt252
(unnamed)/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt260
simplify!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt2170
run-improve43/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3390
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.0/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.0/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128