How to handle symbols in LISP

Two simple ways to transform a symbol name to a string in LISP are to call the function symbol-name or the function string. E.g.,

  USER(1): (symbol-name '_np)
  "_NP"

  USER(2): (string '_np)
  "_NP"

Note that the result is always uppercase.

Then you can use the usual sequence handling functions, such as subseq or find, to manipulate the resulting strings.

  USER(3): (subseq "abcd" 2 4)
  "cd"

Once you have the string that corresponds to a symbol name, you can use either the function read-from-string or the function intern to convert it to a symbol.

  USER(5): (read-from-string "aBc")
  ABC
  3

  USER(6): (intern "ABC")
  ABC
  :INTERNAL

  USER(8): (intern "aBc")
  |aBc|
  NIL

You can also break a string into a list of characters, using the function coerce:

  USER(10): (coerce "ABC" 'list)
  (#\A #\B #\C)

Then you can apply character equality checks such as char-equal and char=. (eq, eql, and equal will also work.) And you can put characters back together into a string by again using the coerce function:

  USER(12): (coerce '(#\A #\B #\C) 'string)
  "ABC"