Hoon Project Euler 9, attempt #1 - `nest-fail`

::  Project Euler 9
::  https://projecteuler.net/problem=9
::
::  > A Pythagorean triplet is a set of three natural numbers, a < b < c, for
::  > which,
::  > >             a2 + b2 = c2
::  > For example, 3^2 + 4^2 = 9 + 16 = 25 = 5^2.
::  > There exists exactly one Pythagorean triplet for which a + b + c = 1000.
::  > Find the product abc.
::
/?  310
::
!:
::
:-  %say  |=  *
:-  %noun
=<  (find-pythagorean-triplet-abc-sum-eq-one-thousand [1 1 998])
::
!.
::
|%
++  find-pythagorean-triplet-abc-sum-eq-one-thousand
  |=  {a/@u b/@u c/@u}                                  :: gate, takes 3 numbers
  =|  p/@u                                              :: product, abc, set l8r
  |-  ^-  @u                                            :: loop, prod is 1 num.
  ?:  p  p                                              :: if p, produce p (abc)
  ?>  =((add (add a b) c) 1.000)                        :: else, sure a+b+c=1000
  %=  $                                                 :: call loop.
    a  |-  ^-  @u                                       :: a -> new loop product
       ?:  =((add (mul a a) (mul b b)) (mul c c))       :: if pythagorean trip.,
         ~&  [a b c]                                    :: prints cell [a b c].
         ^$(p (mul (mul a b) c))                        :: p -> abc (outer loop)
       ?:  =(b c)                                       :: else, if no combos =,
         +(a)                                           :: increment a.
       $(b +(b), c (dec c))                             :: else, this loop +b -c
    c  (dec c)                                          :: c -> decrement c.
  ==
--



> +examples/euler9
/~rep/home/~2017.2.6..22.48.38..23d6/arvo/ford:<[1.211 24].[1.211 52]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[13 1].[38 3]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[15 1].[38 3]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[15 11].[38 3]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[16 1].[38 3]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[17 1].[38 3]>
/~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/0/gen/examples/euler9:<[19 1].[38 3]>
nest-fail
ford: core /~difmyn-tipsut-ricnec-fidped--tadbex-watten-disfet-witbyn/home/~2017.2.25..23.30.05..9735/gen/examples/euler9