Hint:  [Link]
/home/pi/work/misc/nimpi/nimcache/lamp.o: In function `NimMainModule':
lamp.c:(.text+0x348): undefined reference to `piDigitalPWM'
collect2: error: ld returned 1 exit status
Error: execution of an external program failed: 'gcc   -o /home/pi/work/misc/nimpi/lamp  /home/pi/work/misc/nimpi/nimcache/wiringPiWrap.o /home/pi/work/misc/nimpi/nimcache/lamp.o /home/pi/work/misc/nimpi/nimcache/stdlib_system.o /home/pi/work/misc/nimpi/nimcache/wiringPiNim_wiringPiNim.o /home/pi/work/misc/nimpi/nimcache/stdlib_os.o /home/pi/work/misc/nimpi/nimcache/stdlib_strutils.o /home/pi/work/misc/nimpi/nimcache/stdlib_parseutils.o /home/pi/work/misc/nimpi/nimcache/stdlib_math.o /home/pi/work/misc/nimpi/nimcache/stdlib_algorithm.o /home/pi/work/misc/nimpi/nimcache/stdlib_times.o /home/pi/work/misc/nimpi/nimcache/stdlib_posix.o /home/pi/work/misc/nimpi/nimcache/stdlib_ospaths.o  -lwiringPi -lm -lrt   -ldl'
pi@rath:~/work/misc/nimpi$