4.4.1 - redo use new system - db input
4.4.1 - database input
ex 4.55 - done
ex 4.56 - done
4.4.1 - fix: missing rule for prolog prog
ex 4.57 - done
ex 4.58 - done
ex 4.59 - done
4.4.1 - rules
ex 4.60 - done
make each solution a module

Seems these problems tend to refer to each other
additionally some hlint warnings are fixed
Problem11 - done
Problem12 - done
Problem13 - done
Problem14 - done
Problem15 - done
Problem16 - done
Problem17 - done
Problem18 - done
Problem19 - done