. sandbox
cat <<-'EOF' > db.pl
 :- print(22),nl.
 weather is outlook,  $ temp,  $ humidity,  windy,  < play .
              sunny,      85,          85,  false,       no.
              sunny,      80,          90,   true,       no.
           overcast,      83,          86,  false,      yes.
              rainy,      70,          96,  false,      yes.
              rainy,      68,          80,  false,      yes.
              rainy,      65,          70,   true,       no.
           overcast,      64,          65,   true,      yes.
              sunny,      72,          95,  false,       no.
              sunny,      69,          70,  false,      yes.
              rainy,      75,          80,  false,      yes.
              sunny,      75,          70,   true,      yes.
           overcast,      72,          90,   true,      yes.
           overcast,      81,          75,  false,      yes.
              rainy,      71,          91,   true,       no.
EOF

less db.pl

cp db.pl ~/tmp
cd $Here
cd ..
swipl -f main.pl -f $Tmp/db.pl -g 'print(1),halt'