my @words = 'words.txt'.IO.slurp.words.grep: *.chars > 6;
my %words = @words.pairs.invert;
put join "\n", @words.map: { %words{$_}:delete and sprintf "%10s ↔ %s", $_, .flip if ($_ ne .flip) && %words{.flip} }
Output:
amaroid ↔ diorama
degener ↔ reneged
deifier ↔ reified
deliver ↔ reviled
dessert ↔ tressed
desserts ↔ stressed
deviler ↔ relived
dioramas ↔ samaroid
gateman ↔ nametag
leveler ↔ relevel
pat-pat ↔ tap-tap
redrawer ↔ rewarder
reknits ↔ stinker
relever ↔ reveler
reliver ↔ reviler
revotes ↔ setover
sallets ↔ stellas
