?

\[x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}} \]
(FPCore (x y z t a)
 :precision binary64
 (- x (/ (- y z) (/ (+ (- t z) 1.0) a))))
double code(double x, double y, double z, double t, double a) {
	return x - ((y - z) / (((t - z) + 1.0) / a));
}
real(8) function code(x, y, z, t, a)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8), intent (in) :: a
    code = x - ((y - z) / (((t - z) + 1.0d0) / a))
end function
public static double code(double x, double y, double z, double t, double a) {
	return x - ((y - z) / (((t - z) + 1.0) / a));
}
def code(x, y, z, t, a):
	return x - ((y - z) / (((t - z) + 1.0) / a))
function code(x, y, z, t, a)
	return Float64(x - Float64(Float64(y - z) / Float64(Float64(Float64(t - z) + 1.0) / a)))
end
function tmp = code(x, y, z, t, a)
	tmp = x - ((y - z) / (((t - z) + 1.0) / a));
end
code[x_, y_, z_, t_, a_] := N[(x - N[(N[(y - z), $MachinePrecision] / N[(N[(N[(t - z), $MachinePrecision] + 1.0), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}}

Reproduce?

Please include this information when filing a bug report:

herbie shell --seed 2023033 
(FPCore (x y z t a)
  :name "Graphics.Rendering.Chart.SparkLine:renderSparkLine from Chart-1.5.3"
  :precision binary64

  :herbie-target
  (- x (* (/ (- y z) (+ (- t z) 1.0)) a))

  (- x (/ (- y z) (/ (+ (- t z) 1.0) a))))

Backtrace

map: contract violation expected: list? given: #<eof>LC
gen-map/usr/share/racket/collects/racket/private/map.rkt2572
run-egglog/home/nightlies/herbie/oflatt-egglog-ctx/src/egglog/run-egglog.rkt14560
run-simplify-input/home/nightlies/herbie/oflatt-egglog-ctx/src/core/simplify.rkt730
simplify-batch/home/nightlies/herbie/oflatt-egglog-ctx/src/core/simplify.rkt480
(unnamed)/usr/share/racket/collects/racket/contract/private/arrow-higher-order.rkt37933
simplify!/home/nightlies/herbie/oflatt-egglog-ctx/src/patch.rkt2460
patch-table-run/home/nightlies/herbie/oflatt-egglog-ctx/src/patch.rkt3180
(unnamed)/usr/share/racket/collects/racket/contract/private/arrow-val-first.rkt48618
run-iter!/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt2620
mutate!/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt3720
run-improve!/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt3200
run-herbie/home/nightlies/herbie/oflatt-egglog-ctx/src/sandbox.rkt570
(unnamed)/home/nightlies/herbie/oflatt-egglog-ctx/src/sandbox.rkt1336
(unnamed)/usr/share/racket/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/share/racket/pkgs/profile-lib/main.rkt90
(unnamed)/usr/share/racket/collects/racket/engine.rkt4224