use strict;
use warnings;
use 5.012;

my @array = (
   'GAP_SPAN09 - GAP SPAN base (Scratch Testing [TSMC11] : tsmc11_wld(sxfatd12j))',
   'GAP_SPAN03 - GAP SPAN base (DFD E2E Testing [TSPAN04] : tspan04-dfdint-wld(sxfamd6f))',
   'OS_WLI02 - POS_WLI02 Web Logic Integrator',
);

my @results = map{(split / - /)[0]} @array;
say for @results;