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tutorial: Remove confusing discussion about semicolons

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This takes up a lot of words and isn't very clear. The previous
discussion gets they idea across.

/cc: #4217
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Brian Anderson 2012-12-20 02:54:21 -08:00
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@ -308,46 +308,6 @@ fn is_four(x: int) -> bool {
}
~~~~
If all those things are expressions, you might conclude that you have
to add a terminating semicolon after *every* statement, even ones that
are not traditionally terminated with a semicolon in C (like `while`).
That is not the case, though. Expressions that end in a block only
need a semicolon if that block contains a trailing expression. `while`
loops do not allow trailing expressions, and `if` statements tend to
only have a trailing expression when you want to use their value for
something—in which case you'll have embedded it in a bigger statement.
~~~
# fn foo() -> bool { true }
# fn bar() -> bool { true }
# fn baz() -> bool { true }
// `let` is not an expression, so it is semicolon-terminated;
let x = foo();
// When used in statement position, bracy expressions do not
// usually need to be semicolon terminated
if x {
bar();
} else {
baz();
} // No semi-colon
// Although, if `bar` and `baz` have non-nil return types, and
// we try to use them as the tail expressions, rustc will
// make us terminate the expression.
if x {
bar()
} else {
baz()
}; // Semi-colon to ignore non-nil block type
// An `if` embedded in `let` again requires a semicolon to terminate
// the `let` statement
let y = if x { foo() } else { bar() };
~~~
This may sound intricate, but it is super-useful and will grow on you.
## Types
The basic types include the usual boolean, integral, and floating-point types.