These lazy iterator producing methods are useful when working with
arbitrary sequences and you need to skip or take some number of elements
at the start.
Get rid of the separate opt-in IO class and replace it with a core
System class.
- Remove wren_io.c, wren_io.h, and io.wren.
- Remove the flags that disable it.
- Remove the overloads for print() with different arity. (It was an
experiment, but I don't think it's that useful.)
- Remove IO.read(). That will reappear using libuv in the CLI at some
point.
- Remove IO.time. Doesn't seem to have been used.
- Update all of the tests, docs, etc.
I'm sorry for all the breakage this causes, but I think "System" is a
better name for this class (it makes it natural to add things like
"System.gc()") and frees up "IO" for referring to the CLI's IO module.
* Eliminate "new" reserved word.
* Allow "this" before a method definition to define a constructor.
* Only create a default constructor for classes that don't define one.
The methods Sequence.map and Sequence.where are now implemented using
deferred execution. They return an instance of a new Sequence-derived
class that performs the operation while iterating. This has three main
advantages:
* It can be computationally cheaper when not the whole sequence is
iterated.
* It consumes less memory since it does not store the result in a newly
allocated list.
* They can work on infinite sequences.
Some disadvantages are:
* Iterating the returned iterator will be slightly slower due to
the added indirection.
* You should be aware that modifications made to the original sequence
will affect the returned sequence.
* If you need the result in a list, you now need to call Sequence.list
on the result.
When possible, they return the actual value from the predicate
instead of always just "true" and "false". This matches && and ||
which evaluate to the RHS or LHS when appropriate.
