#O, 13 bytes
O, 13 bytes
i{'+n#*".>"}d Explanation:
i Read standard input into a string and push it onto the stack. { }d For each character in the string... '+ Push "+". n# Convert the character (n) to its ASCII code. * Multiply the "+" by the character code to get the number of +'s needed. ".>" Push the string ".>". In O, the stack is printed after execution, so this prints out the result.