(use-modules (ice-9 rdelim)) (define (file-lines-match? file prefix) (with-input-from-file file (lambda () (catch 'found (lambda () (let loop ((line (read-line))) (cond ((eof-object? line) #false) ((string-prefix? prefix line) (throw 'found)) (else (loop (read-line)))))) (const #true)))))