Maybe you know or can make some assumptions about the general conditions required for your program.

Your code (with the above mentioned correction for using 'eq' instead of '==') might be already ok; it might be not ok if the files to compare could be large/huge.

Then some other possible restrictions/caveats would come up:

- would there be any restrictions on how much memory is available ?
- would it be important to get a quick answer or is it no problem to let the processing take some time ?
- would 'similarity' mean 'equality' (as in your code), or would a somewhat 'softer' test be needed (allowing for a variable number of whitespaces, linebreaks, casing, ...) ?

Considering such issues would make it possible to know if the solution drafted above is perfectly enough or if it would need refinements.