\[\left(x + x\right) - 1\]
\left(x + x\right) - 1
(FPCore (x) :precision binary64 (- (+ x x) 1.0))
double code(double x) {
	return ((double) (((double) (x + x)) - 1.0));
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020203 
(FPCore (x)
  :name "Data.Random.Distribution.Normal:doubleStdNormalZ from random-fu-0.2.6.2"
  :precision binary64
  (- (+ x x) 1.0))

Backtrace

first: contract violation expected: (and/c list? (not/c empty?)) given: '()LC
batch-eval-progs/data/pavpan/nightlies/herbie/cleanup/src/programs.rkt1070
batch-errors/data/pavpan/nightlies/herbie/cleanup/src/points.rkt1690
atab-add-altns/data/pavpan/nightlies/herbie/cleanup/src/core/alt-table.rkt1940
(unnamed)/opt/racket-7.5/collects/racket/contract/private/arrow-val-first.rkt48618
finalize-iter!/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt2730
run-iter!/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt3410
for-loop/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt3794
run-improve41/data/pavpan/nightlies/herbie/cleanup/src/mainloop.rkt3600
.../more-scheme.rkt:261:28unknown
run/opt/racket-7.5/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.5/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.5/collects/racket/private/more-scheme.rkt26128

Reproduce

herbie shell --seed 2020203 
(FPCore (x)
  :name "Data.Random.Distribution.Normal:doubleStdNormalZ from random-fu-0.2.6.2"
  :precision binary64
  (- (+ x x) 1.0))