15.25.6.6 ’for-as-across’

This is the fifth of seven ‘for/as’ syntaxes.

for var [type-spec] across vector
 as var [type-spec] across vector

• This construct binds the variable var to the value of each element in the array vector.
• The loop keyword ‘across’ marks the array vector; ‘across’ is used as a preposition in this syntax. Iteration stops when there are no more elements in the specified array that can be referenced.
• Some implementations might use a [user-supplied-GLS] the special form in the vector form to produce more efficient code.

(loop for char across (the simple-string (find-message port))
      do (write-char char stream))