<oerjan> learn A zygohistomorphic prepromorphism is used when you really need both semi-mutual recursion and history and to repeatedly apply a natural transformation as you get deeper into the functor.

#!/bin/sh
allquotes | if [ "$1" ]; then
    if expr "$1" + 0 >/dev/null 2>&1; then
        sed "$1q;d"
    else
        grep -P -i -- "$1"
    fi
else shuf -n 1; fi