SML Check if String starts with letter

Question

I'm very new to SMLNJ and was wondering how you go about something simple as checking if a string starts with a letter or starts with a " and then returning true or false.

Example: If a string looks like

"aaaaa" then return true
"\"aaaa\"" then return true
"25aaaa" then return false

Answer 1

You can cobble together a solution using some Standard Basis Library functions:

fun checkFirst s =
   let val c = String.sub(s,0) in
        c = #"\"" orelse Char.isAlpha(c) 
   end;