So I’ve just completed the first challenge from dailyprogrammer. It’s a pretty easy challenge but that didn’t stop me WTF’ing all the way through.

The challenge

The challenge itself was simple (embarrasingly simple)

Write a program that will ask the users name, age, and reddit username. Have it tell them the information back, in the format: your name is (blank), you are (blank) years old, and your username is (blank)”

Questions

Here are the questions I asked myself throughout and the answers that I (think) are correct

• How do I display stuff?
  • Use the (display) procedure
• How do I read user input
  • Use (read). Note that I think newer schemes actually have something called (read-line) which casts the user input from a symbol to a string for you
• Why is the variable stored from (read) not a string?
  • As mentioned before, it’s returned as a symbol, you need to convert it yourself
• How can I convert symbols?
  • Use (symbol->string) to convert a symbol to a string
• How do I concatenate strings
  • use (string-append)
• What is the scheme filetype extension so I can actually save my work?
  • I’m using ‘.scm’ though I could be wrong…

My solution

(display "What is your name")
(define name (symbol->string (read)))

(display "What is your age")
(define age (number->string(read)))

(display "What is your username")
(define user (symbol->string(read)))

(display 
 (string-append 
  "Your name is " name
  " and you are " age " years old"
  " and your username is " user))

Unanswered questions

• Why does (read) bring back a number if the input is a number? Why not a symbol?

• WTF is a symbol?

Things I enjoyed

I like the naming conventions and consistency of the procedures. You barely have to look at the documentation because your guess of a procedure name usually is the procedure name.

For example, I had no idea how to convert a number to a string. I used

number->string

and hey presto!