Attempt to code eval loop in sh

eval.sh

#!/bin/sh 

# Futile attempts keep BUG below to not potentially exit the script.
set +e +E    
trap '' ERR

# displays the prompt in light cyan.
# TODO: http://stackoverflow.com/q/6788777/7507 
    
echo -e "\e[00;36mEnter expressions, [Ctrl-C] to exit\e[00m"
while :
do
    echo -en "\e[00;36m=> \e[00m"
    read expression
    # BUG: If the expression is invalid, exits the script
    echo $((${expression}))
done