Reads the file to which file-specifier resolves one line at a time (using read-line) and applies function to each line. File-specifier can be a string pointing to a file, a logical or physical pathname or a stream.
| map-lines-in-file < t > < structure-class > |
| map-lines-in-file < t > < string > |
| map-lines-in-file < t > < t > |