Since `dropFirst` does not return an `Optional`,
`unsafeUnwrap(xs.dropFirst())` first implicitly wraps result of
`dropFirst` into an optional and then calls `unsafeUnwrap` on that.
rdar://problem/21663830
Add the following new requirements to SequenceType with default implementations:
- dropFirst(n)
- dropLast(n)
- prefix(n)
- suffix(n)
- split(n)
In addition, provide specialized default implementations of these for CollectionTypes with forward, bidirectional, and random-access Index types where possible.
Add the following new requirements to CollectionType with default implementations:
- prefixThrough(n)
- prefixUpTo(n)
- suffixFrom(n)
- split() // isSeparator closure
Add the following convenience APIs:
- dropFirst() -> calls dropFirst(1)
- dropLast() -> calls dropLast(1)
Add a tentative underscored API:
- split() // takes Equatable separator.
Some APIs have undefined behavior when creating slices where the endpoints go beyond the bounds of the underlying collection. This will be fixed later by trapping creation of slices with invalid indices (rdar://problem/21822657).
Swift SVN r30371
includes a number of QoI things to help people write the correct code. I will commit
the testcase for it as the next patch.
The bulk of this patch is moving the stdlib, testsuite and validation testsuite to
the new syntax. I moved a few uses of "as" patterns back to as? expressions in the
stdlib as well.
Swift SVN r27959
The rule changes are as follows:
* All functions (introduced with the 'func' keyword) have argument
labels for arguments beyond the first, by default. Methods are no
longer special in this regard.
* The presence of a default argument no longer implies an argument
label.
The actual changes to the parser and printer are fairly simple; the
rest of the noise is updating the standard library, overlays, tests,
etc.
With the standard library, this change is intended to be API neutral:
I've added/removed #'s and _'s as appropriate to keep the user
interface the same. If we want to separately consider using argument
labels for more free functions now that the defaults in the language
have shifted, we can tackle that separately.
Fixes rdar://problem/17218256.
Swift SVN r27704
