code review 824045: Language FAQ: update the entry on exceptions.

doc/go_lang_faq.html

 <!-- Language Design FAQ -->
 
 <h2 id="origins">Origins</h2>
 
 <h3 id="history">
 What is the history of the project?</h3>
 <p>
 Robert Griesemer, Rob Pike and Ken Thompson started sketching the
 goals for a new language on the white board on September 21, 2007.
 Within a few days the goals had settled into a plan to do something
@@ skipping 264 matching lines @@
 (with explicit unboxing) mean in many cases it is possible to write
 code that does what generics would enable, if less smoothly.
 </p>
 <p>
 This remains an open issue.
 </p>
 
 <h3 id="exceptions">
 Why does Go not have exceptions?</h3>
 <p>
 We believe that coupling the usual idea of exceptions to a control

[iant, 2010/04/07 23:02:33]

I think you can omit "the usual idea of".

 structure, as in the <code>try-catch-finally</code> idiom, results in
 convoluted code.  It also tends to encourage programmers to label
 too many ordinary errors, such as failing to open a file, as
 exceptional.  And then the type system gets mixed in.

[iant, 2010/04/07 23:02:33]

I think I know what you mean by the type system comment, but, as you hint, it
seems orthogonal to rest of the paragraph.  I'm not sure it adds anything.

 </p>
 <p>
 Go takes a different approach.  Instead of exceptions, it has couple

[iant, 2010/04/07 23:02:33]

s/has couple/has a couple/

 of built-in functions to signal and recover from truly exceptional
 conditions.  The recovery mechanism is executed only as part of a
 function's state being torn down after an error, which is sufficient
-to handle catastrophe but awkward enough to discourage overuse.

[iant, 2010/04/07 23:02:33]

Maybe s/awkward enough to discourage overuse/avoids conflating exceptions with a
control structure/

+to handle catastrophe but requires no extra control structures and,
+when used well, can result in clean error-handling code.
 </p>
 
 <h3 id="assertions">
 Why does Go not have assertions?</h3>
 <p>
 This is answered in the general <a href="go_faq.html#Where_is_assert">FAQ</a>.
 </p>
 
 <h2 id="types">Types</h2>
 
@@ skipping 174 matching lines @@
 synchronized.  Therefore requiring that all map operations grab a mutex would slow
 down most programs and add safety to few.  This was not an easy decision,
 however, since it means uncontrolled map access can crash the program.
 </p>
 
 <p>
 The language does not preclude atomic map updates.  When required, such
 as when hosting an untrusted program, the implementation could interlock
 map access.
 </p>