move errno -> IoError converter into std, bubble up OSRng errors
Also adds a general errno -> `~str` converter to `std::os`, and makes the failure messages for the things using `OSRng` (e.g. (transitively) the task-local RNG, meaning hashmap initialisation failures aren't such a black box).
The various ...Rng::new() methods can hit IO errors from the OSRng they use,
and it seems sensible to expose them at a higher level. Unfortunately, writing
e.g. `StdRng::new().unwrap()` gives a much poorer error message than if it
failed internally, but this is a problem with all `IoResult`s.
This removes the `attr` matcher and adds a `meta` matcher. The previous `attr`
matcher is now ambiguous because it doesn't disambiguate whether it means inner
attribute or outer attribute.
The new behavior can still be achieved by taking an argument of the form
`#[$foo:meta]` (the brackets are part of the macro pattern).
Closes#13067
It turns out that on linux, and possibly other platforms, child processes will
continue to accept signals until they have been *reaped*. This means that once
the child has exited, it will succeed to receive signals until waitpid() has
been invoked on it.
This is unfortunate behavior, and differs from what is seen on OSX and windows.
This commit changes the behavior of Process::signal() to be the same across
platforms, and updates the documentation of Process::kill() to note that when
signaling a foreign process it may accept signals until reaped.
Implementation-wise, this invokes waitpid() with WNOHANG before each signal to
the child to ensure that if the child has exited that we will reap it. Other
possibilities include installing a SIGCHLD signal handler, but at this time I
believe that that's too complicated.
Closes#13124
This commit contains an implementation of synchronous, bounded channels for
Rust. This is an implementation of the proposal made last January [1]. These
channels are built on mutexes, and currently focus on a working implementation
rather than speed. Receivers for sync channels have select() implemented for
them, but there is currently no implementation of select() for sync senders.
Rust will continue to provide both synchronous and asynchronous channels as part
of the standard distribution, there is no intent to remove asynchronous
channels. This flavor of channels is meant to provide an alternative to
asynchronous channels because like green tasks, asynchronous channels are not
appropriate for all situations.
[1] - https://mail.mozilla.org/pipermail/rust-dev/2014-January/007924.html
`Vec` is now used for the internal buffer instead of `~[]`. Some module
level documentation somehow ended up attached to `BufferedReader` so I
fixed that as well.
I've found a common use case being to fill a slice (not an owned vector)
completely with bytes. It's posible for short reads to happen, and if you're
trying to get an exact number of bytes then this helper will be useful.
These methods can be mistaken for general "read some bytes" utilities when
they're actually only meant for reading an exact number of bytes. By renaming
them it's much clearer about what they're doing without having to read the
documentation.
Closes#12892
These methods can be mistaken for general "read some bytes" utilities when
they're actually only meant for reading an exact number of bytes. By renaming
them it's much clearer about what they're doing without having to read the
documentation.
Closes#12892
this comes from a discussion on IRC where the split between stdin and stdout
seemed unnatural, and the fact that reading on stdin won't flush stdout, which
is unlike every other language (including C's stdio).
This commit moves all logging out of the standard library into an external
crate. This crate is the new crate which is responsible for all logging macros
and logging implementation. A few reasons for this change are:
* The crate map has always been a bit of a code smell among rust programs. It
has difficulty being loaded on almost all platforms, and it's used almost
exclusively for logging and only logging. Removing the crate map is one of the
end goals of this movement.
* The compiler has a fair bit of special support for logging. It has the
__log_level() expression as well as generating a global word per module
specifying the log level. This is unfairly favoring the built-in logging
system, and is much better done purely in libraries instead of the compiler
itself.
* Initialization of logging is much easier to do if there is no reliance on a
magical crate map being available to set module log levels.
* If the logging library can be written outside of the standard library, there's
no reason that it shouldn't be. It's likely that we're not going to build the
highest quality logging library of all time, so third-party libraries should
be able to provide just as high-quality logging systems as the default one
provided in the rust distribution.
With a migration such as this, the change does not come for free. There are some
subtle changes in the behavior of liblog vs the previous logging macros:
* The core change of this migration is that there is no longer a physical
log-level per module. This concept is still emulated (it is quite useful), but
there is now only a global log level, not a local one. This global log level
is a reflection of the maximum of all log levels specified. The previously
generated logging code looked like:
if specified_level <= __module_log_level() {
println!(...)
}
The newly generated code looks like:
if specified_level <= ::log::LOG_LEVEL {
if ::log::module_enabled(module_path!()) {
println!(...)
}
}
Notably, the first layer of checking is still intended to be "super fast" in
that it's just a load of a global word and a compare. The second layer of
checking is executed to determine if the current module does indeed have
logging turned on.
This means that if any module has a debug log level turned on, all modules
with debug log levels get a little bit slower (they all do more expensive
dynamic checks to determine if they're turned on or not).
Semantically, this migration brings no change in this respect, but
runtime-wise, this will have a perf impact on some code.
* A `RUST_LOG=::help` directive will no longer print out a list of all modules
that can be logged. This is because the crate map will no longer specify the
log levels of all modules, so the list of modules is not known. Additionally,
warnings can no longer be provided if a malformed logging directive was
supplied.
The new "hello world" for logging looks like:
#[phase(syntax, link)]
extern crate log;
fn main() {
debug!("Hello, world!");
}
This commit shreds all remnants of libextra from the compiler and standard
distribution. Two modules, c_vec/tempfile, were moved into libstd after some
cleanup, and the other modules were moved to separate crates as seen fit.
Closes#8784Closes#12413Closes#12576
This is something that is plausibly useful, and is provided by libuv. This is
not currently surfaced as part of the `TcpStream` type, but it may possibly
appear in the future. For now only the raw functionality is provided through the
Rtio objects.
This is something that is plausibly useful, and is provided by libuv. This is
not currently surfaced as part of the `TcpStream` type, but it may possibly
appear in the future. For now only the raw functionality is provided through the
Rtio objects.
As mentioned in #6109, ```mkdir_recursive``` doesn't really need to use recursive calls, so here is an iterative version.
The other points of the proposed overhaul (renaming and existing permissions) still need to be resolved.
I also bundled an iterative ```rmdir_recursive```, for the same reason.
Please do not hesitate to provide feedback on style as this is my first code change in rust.
Most IO related functions return an IoResult so that the caller can handle failure in whatever way is appropriate. However, the `lines`, `bytes`, and `chars` iterators all supress errors. This means that code that needs to handle errors can't use any of these iterators. All three of these iterators were updated to produce IoResults.
Fixes#12368
Most IO related functions return an IoResult so that the caller can handle failure
in whatever way is appropriate. However, the `lines`, `bytes`, and `chars` iterators all
supress errors. This means that code that needs to handle errors can't use any of these
iterators. All three of these iterators were updated to produce IoResults.
Fixes#12368
This replaces it with a manual "task rng" using XorShift and a crappy
seeding mechanism. Theoretically good enough for the purposes
though (unique for tests).
Similarly to #12422 which made stdin buffered by default, this commit makes the
output streams also buffered by default. Now that buffered writers will flush
their contents when they are dropped, I don't believe that there's no reason why
the output shouldn't be buffered by default, which is what you want in 90% of
cases.
As with stdin, there are new stdout_raw() and stderr_raw() functions to get
unbuffered streams to stdout/stderr.
It's still not entirely clear what should happen if there was an error when
flushing, but I'm deferring that decision to #12628. I believe that it's crucial
for the usefulness of buffered writers to be able to flush on drop. It's just
too easy to forget to flush them in small one-off use cases.
cc #12628
Formatting via reflection has been a little questionable for some time now, and
it's a little unfortunate that one of the standard macros will silently use
reflection when you weren't expecting it. This adds small bits of code bloat to
libraries, as well as not always being necessary. In light of this information,
this commit switches assert_eq!() to using {} in the error message instead of
{:?}.
In updating existing code, there were a few error cases that I encountered:
* It's impossible to define Show for [T, ..N]. I think DST will alleviate this
because we can define Show for [T].
* A few types here and there just needed a #[deriving(Show)]
* Type parameters needed a Show bound, I often moved this to `assert!(a == b)`
* `Path` doesn't implement `Show`, so assert_eq!() cannot be used on two paths.
I don't think this is much of a regression though because {:?} on paths looks
awful (it's a byte array).
Concretely speaking, this shaved 10K off a 656K binary. Not a lot, but sometime
significant for smaller binaries.
This lowers the #[allow(missing_doc)] directive into some of the lower modules
which are less mature. Most I/O modules now require comprehensive documentation.
The compiler itself doesn't necessarily need any features of green threading
such as spawning tasks and lots of I/O, so libnative is slightly more
appropriate for rustc to use itself.
This should also help the rusti bot which is currently incompatible with libuv.
This weeds out a bunch of warnings building stdtest on windows, and it also adds
a check! macro to the io::fs tests to help diagnose errors that are cropping up
on windows platforms as well.
cc #12516
This patch series does a couple things:
* replaces manual `Hash` implementations with `#[deriving(Hash)]`
* adds `Hash` back to `std::prelude`
* minor cleanup of whitespace and variable names.
Turns out the `timeout` command was exiting immediately because it didn't like
its output piped. Instead use `ping` repeatedly to get a process that will sleep
for awhile.
cc #12516
These two tests are notoriously flaky on the windows bots right now, so I'm
ignoring them until I can investigate them some more. The truncate_works test
has been flaky for quite some time, but it has gotten much worse recently. The
test_exists test has been flaky since the recent std::run rewrite landed.
Finally, the "unix pipe" test failure is a recent discovery on the try bots. I
haven't seen this failing much, but better safe than sorry!
cc #12516
This commit removes deriving(ToStr) in favor of deriving(Show), migrating all impls of ToStr to fmt::Show.
Most of the details can be found in the first commit message.
Closes#12477
The std::run module is a relic from a standard library long since past, and
there's not much use to having two modules to execute processes with where one
is slightly more convenient. This commit merges the two modules, moving lots of
functionality from std::run into std::io::process and then deleting
std::run.
New things you can find in std::io::process are:
* Process::new() now only takes prog/args
* Process::configure() takes a ProcessConfig
* Process::status() is the same as run::process_status
* Process::output() is the same as run::process_output
* I/O for spawned tasks is now defaulted to captured in pipes instead of ignored
* Process::kill() was added (plus an associated green/native implementation)
* Process::wait_with_output() is the same as the old finish_with_output()
* destroy() is now signal_exit()
* force_destroy() is now signal_kill()
Closes#2625Closes#10016
The std::run module is a relic from a standard library long since past, and
there's not much use to having two modules to execute processes with where one
is slightly more convenient. This commit merges the two modules, moving lots of
functionality from std::run into std::io::process and then deleting
std::run.
New things you can find in std::io::process are:
* Process::new() now only takes prog/args
* Process::configure() takes a ProcessConfig
* Process::status() is the same as run::process_status
* Process::output() is the same as run::process_output
* I/O for spawned tasks is now defaulted to captured in pipes instead of ignored
* Process::kill() was added (plus an associated green/native implementation)
* Process::wait_with_output() is the same as the old finish_with_output()
* destroy() is now signal_exit()
* force_destroy() is now signal_kill()
Closes#2625Closes#10016
This commit changes the ToStr trait to:
impl<T: fmt::Show> ToStr for T {
fn to_str(&self) -> ~str { format!("{}", *self) }
}
The ToStr trait has been on the chopping block for quite awhile now, and this is
the final nail in its coffin. The trait and the corresponding method are not
being removed as part of this commit, but rather any implementations of the
`ToStr` trait are being forbidden because of the generic impl. The new way to
get the `to_str()` method to work is to implement `fmt::Show`.
Formatting into a `&mut Writer` (as `format!` does) is much more efficient than
`ToStr` when building up large strings. The `ToStr` trait forces many
intermediate allocations to be made while the `fmt::Show` trait allows
incremental buildup in the same heap allocated buffer. Additionally, the
`fmt::Show` trait is much more extensible in terms of interoperation with other
`Writer` instances and in more situations. By design the `ToStr` trait requires
at least one allocation whereas the `fmt::Show` trait does not require any
allocations.
Closes#8242Closes#9806
These two containers are indeed collections, so their place is in
libcollections, not in libstd. There will always be a hash map as part of the
standard distribution of Rust, but by moving it out of the standard library it
makes libstd that much more portable to more platforms and environments.
This conveniently also removes the stuttering of 'std::hashmap::HashMap',
although 'collections::HashMap' is only one character shorter.
One of the most common ways to use the stdin stream is to read it line by line
for a small program. In order to facilitate this common usage pattern, this
commit changes the stdin() function to return a BufferedReader by default. A new
`stdin_raw()` method was added to get access to the raw unbuffered stream.
I have not changed the stdout or stderr methods because they are currently
unable to flush in their destructor, but #12403 should have just fixed that.
This is in preparation to remove the implementations of ToStrRadix in integers, and to remove the associated logic from `std::num::strconv`.
The parts that still need to be liberated are:
- `std::fmt::Formatter::runplural`
- `num::{bigint, complex, rational}`
This "bubble up an error" macro was originally named if_ok! in order to get it
landed, but after the fact it was discovered that this name is not exactly
desirable.
The name `if_ok!` isn't immediately clear that is has much to do with error
handling, and it doesn't look fantastic in all contexts (if if_ok!(...) {}). In
general, the agreed opinion about `if_ok!` is that is came in as subpar.
The name `try!` is more invocative of error handling, it's shorter by 2 letters,
and it looks fitting in almost all circumstances. One concern about the word
`try!` is that it's too invocative of exceptions, but the belief is that this
will be overcome with documentation and examples.
Close#12037
One of the most common ways to use the stdin stream is to read it line by line
for a small program. In order to facilitate this common usage pattern, this
commit changes the stdin() function to return a BufferedReader by default. A new
`stdin_raw()` method was added to get access to the raw unbuffered stream.
I have not changed the stdout or stderr methods because they are currently
unable to flush in their destructor, but #12403 should have just fixed that.
* Implementation of pipe_win32 filled out for libnative
* Reorganize pipes to be clone-able
* Fix a few file descriptor leaks on error
* Factor out some common code into shared functions
* Make use of the if_ok!() macro for less indentation
Closes#11201
This is useful in contexts like this:
```rust
let size = rdr.read_be_i32() as uint;
let mut limit = LimitReader::new(rdr.by_ref(), size);
let thing = read_a_thing(&mut limit);
assert!(limit.limit() == 0);
```
This is useful in contexts like this:
let size = rdr.read_be_i32() as uint;
let mut limit = LimitReader::new(rdr.by_ref(), size);
let thing = read_a_thing(&mut limit);
assert!(limit.limit() == 0);
When tests fail, their stdout and stderr is printed as part of the summary, but
this helps suppress failure messages from #[should_fail] tests and generally
clean up the output of the test runner.
This adopts the rules posted in #10432:
1. If a seek position is negative, then an error is generated
2. Seeks beyond the end-of-file are allowed. Future writes will fill the gap
with data and future reads will return errors.
3. Seeks within the bounds of a file are fine.
Closes#10432
This adopts the rules posted in #10432:
1. If a seek position is negative, then an error is generated
2. Seeks beyond the end-of-file are allowed. Future writes will fill the gap
with data and future reads will return errors.
3. Seeks within the bounds of a file are fine.
Closes#10432
This, the Nth rewrite of channels, is not a rewrite of the core logic behind
channels, but rather their API usage. In the past, we had the distinction
between oneshot, stream, and shared channels, but the most recent rewrite
dropped oneshots in favor of streams and shared channels.
This distinction of stream vs shared has shown that it's not quite what we'd
like either, and this moves the `std::comm` module in the direction of "one
channel to rule them all". There now remains only one Chan and one Port.
This new channel is actually a hybrid oneshot/stream/shared channel under the
hood in order to optimize for the use cases in question. Additionally, this also
reduces the cognitive burden of having to choose between a Chan or a SharedChan
in an API.
My simple benchmarks show no reduction in efficiency over the existing channels
today, and a 3x improvement in the oneshot case. I sadly don't have a
pre-last-rewrite compiler to test out the old old oneshots, but I would imagine
that the performance is comparable, but slightly slower (due to atomic reference
counting).
This commit also brings the bonus bugfix to channels that the pending queue of
messages are all dropped when a Port disappears rather then when both the Port
and the Chan disappear.
This is a fairly trivial (but IMHO handy) change to implement IterBytes for IpAddr and SocketAddr.
I originally stumbled across this because I wanted to use a SocketAddr as a HashMap key and discovered that I couldn't do it directly. Had to impl IterBytes on a new intermediate type to work around it.
I have a hunch this just deadlocked the windows bots. Due to UDP being a lossy
protocol, I don't think we can guarantee that the server can receive both
packets, so just listen for one of them.
This is part of the overall strategy I would like to take when approaching
issue #11165. The only two I/O objects that reasonably want to be "split" are
the network stream objects. Everything else can be "split" by just creating
another version.
The initial idea I had was the literally split the object into a reader and a
writer half, but that would just introduce lots of clutter with extra interfaces
that were a little unnnecssary, or it would return a ~Reader and a ~Writer which
means you couldn't access things like the remote peer name or local socket name.
The solution I found to be nicer was to just clone the stream itself. The clone
is just a clone of the handle, nothing fancy going on at the kernel level.
Conceptually I found this very easy to wrap my head around (everything else
supports clone()), and it solved the "split" problem at the same time.
The cloning support is pretty specific per platform/lib combination:
* native/win32 - uses some specific WSA apis to clone the SOCKET handle
* native/unix - uses dup() to get another file descriptor
* green/all - This is where things get interesting. When we support full clones
of a handle, this implies that we're allowing simultaneous writes
and reads to happen. It turns out that libuv doesn't support two
simultaneous reads or writes of the same object. It does support
*one* read and *one* write at the same time, however. Some extra
infrastructure was added to just block concurrent writers/readers
until the previous read/write operation was completed.
I've added tests to the tcp/unix modules to make sure that this functionality is
supported everywhere.
* All I/O now returns IoResult<T> = Result<T, IoError>
* All formatting traits now return fmt::Result = IoResult<()>
* The if_ok!() macro was added to libstd
LLVM fails to properly optimize the shifts used to convert the source
value to the right endianess. The resulting assembly copies the value
to the stack one byte at a time even when there's no conversion required
(e.g. u64_to_le_bytes on a little endian machine).
Instead of doing the conversion ourselves using shifts, we can use the
existing intrinsics to perform the endianess conversion and then
transmute the value to get a fixed vector of its bytes.
Before:
test be_i8 ... bench: 21442 ns/iter (+/- 70)
test be_i16 ... bench: 21447 ns/iter (+/- 45)
test be_i32 ... bench: 23832 ns/iter (+/- 63)
test be_i64 ... bench: 26887 ns/iter (+/- 267)
test le_i8 ... bench: 21442 ns/iter (+/- 56)
test le_i16 ... bench: 21448 ns/iter (+/- 36)
test le_i32 ... bench: 23825 ns/iter (+/- 153)
test le_i64 ... bench: 26271 ns/iter (+/- 138)
After:
test be_i8 ... bench: 21438 ns/iter (+/- 10)
test be_i16 ... bench: 21441 ns/iter (+/- 15)
test be_i32 ... bench: 19057 ns/iter (+/- 6)
test be_i64 ... bench: 21439 ns/iter (+/- 34)
test le_i8 ... bench: 21438 ns/iter (+/- 19)
test le_i16 ... bench: 21439 ns/iter (+/- 8)
test le_i32 ... bench: 21439 ns/iter (+/- 19)
test le_i64 ... bench: 21438 ns/iter (+/- 22)
`Times::times` was always a second-class loop because it did not support the `break` and `continue` operations. Its playful appeal (which I liked) was then lost after `do` was disabled for closures. It's time to let this one go.
`Times::times` was always a second-class loop because it did not support the `break` and `continue` operations. Its playful appeal was then lost after `do` was disabled for closures. It's time to let this one go.
I found awkward to have `MutableCloneableVector` and `CloneableIterator` on the one hand, and `CopyableVector` etc. on the other hand.
The concerned traits are:
* `CopyableVector` --> `CloneableVector`
* `OwnedCopyableVector` --> `OwnedCloneableVector`
* `ImmutableCopyableVector` --> `ImmutableCloneableVector`
* `CopyableTuple` --> `CloneableTuple`
The general consensus is that we want to move away from conditions for I/O, and I propose a two-step plan for doing so:
1. Warn about unused `Result` types. When all of I/O returns `Result`, it will require you inspect the return value for an error *only if* you have a result you want to look at. By default, for things like `write` returning `Result<(), Error>`, these will all go silently ignored. This lint will prevent blind ignorance of these return values, letting you know that there's something you should do about them.
2. Implement a `try!` macro:
```
macro_rules! try( ($e:expr) => (match $e { Ok(e) => e, Err(e) => return Err(e) }) )
```
With these two tools combined, I feel that we get almost all the benefits of conditions. The first step (the lint) is a sanity check that you're not ignoring return values at callsites. The second step is to provide a convenience method of returning early out of a sequence of computations. After thinking about this for awhile, I don't think that we need the so-called "do-notation" in the compiler itself because I think it's just *too* specialized. Additionally, the `try!` macro is super lightweight, easy to understand, and works almost everywhere. As soon as you want to do something more fancy, my answer is "use match".
Basically, with these two tools in action, I would be comfortable removing conditions. What do others think about this strategy?
----
This PR specifically implements the `unused_result` lint. I actually added two lints, `unused_result` and `unused_must_use`, and the first commit has the rationale for why `unused_result` is turned off by default.
These are either returned from public functions, and really should
appear in the documentation, but don't since they're private, or are
implementation details that are currently public.
These are either returned from public functions, and really should
appear in the documentation, but don't since they're private, or are
implementation details that are currently public.
Native timers are a much hairier thing to deal with than green timers due to the
interface that we would like to expose (both a blocking sleep() and a
channel-based interface). I ended up implementing timers in three different ways
for the various platforms that we supports.
In all three of the implementations, there is a worker thread which does send()s
on channels for timers. This worker thread is initialized once and then
communicated to in a platform-specific manner, but there's always a shared
channel available for sending messages to the worker thread.
* Windows - I decided to use windows kernel timer objects via
CreateWaitableTimer and SetWaitableTimer in order to provide sleeping
capabilities. The worker thread blocks via WaitForMultipleObjects where one of
the objects is an event that is used to wake up the helper thread (which then
drains the incoming message channel for requests).
* Linux/(Android?) - These have the ideal interface for implementing timers,
timerfd_create. Each timer corresponds to a timerfd, and the helper thread
uses epoll to wait for all active timers and then send() for the next one that
wakes up. The tricky part in this implementation is updating a timerfd, but
see the implementation for the fun details
* OSX/FreeBSD - These obviously don't have the windows APIs, and sadly don't
have the timerfd api available to them, so I have thrown together a solution
which uses select() plus a timeout in order to ad-hoc-ly implement a timer
solution for threads. The implementation is backed by a sorted array of timers
which need to fire. As I said, this is an ad-hoc solution which is certainly
not accurate timing-wise. I have done this implementation due to the lack of
other primitives to provide an implementation, and I've done it the best that
I could, but I'm sure that there's room for improvement.
I'm pretty happy with how these implementations turned out. In theory we could
drop the timerfd implementation and have linux use the select() + timeout
implementation, but it's so inaccurate that I would much rather continue to use
timerfd rather than my ad-hoc select() implementation.
The only change that I would make to the API in general is to have a generic
sleep() method on an IoFactory which doesn't require allocating a Timer object.
For everything but windows it's super-cheap to request a blocking sleep for a
set amount of time, and it's probably worth it to provide a sleep() which
doesn't do something like allocate a file descriptor on linux.
* Reexport io::mem and io::buffered structs directly under io, make mem/buffered
private modules
* Remove with_mem_writer
* Remove DEFAULT_CAPACITY and use DEFAULT_BUF_SIZE (in io::buffered)
cc #11119
* Reexport io::mem and io::buffered structs directly under io, make mem/buffered
private modules
* Remove with_mem_writer
* Remove DEFAULT_CAPACITY and use DEFAULT_BUF_SIZE (in io::buffered)
Major changes:
- Define temporary scopes in a syntax-based way that basically defaults
to the innermost statement or conditional block, except for in
a `let` initializer, where we default to the innermost block. Rules
are documented in the code, but not in the manual (yet).
See new test run-pass/cleanup-value-scopes.rs for examples.
- Refactors Datum to better define cleanup roles.
- Refactor cleanup scopes to not be tied to basic blocks, permitting
us to have a very large number of scopes (one per AST node).
- Introduce nascent documentation in trans/doc.rs covering datums and
cleanup in a more comprehensive way.
The `print!` and `println!` macros are now the preferred method of printing, and so there is no reason to export the `stdio` functions in the prelude. The functions have also been replaced by their macro counterparts in the tutorial and other documentation so that newcomers don't get confused about what they should be using.
The `print!` and `println!` macros are now the preferred method of printing, and so there is no reason to export the `stdio` functions in the prelude. The functions have also been replaced by their macro counterparts in the tutorial and other documentation so that newcomers don't get confused about what they should be using.
