Crystal 0.26.0 released!

09 Aug 2018

Brian J. Cardiff

This release is focused on polishing APIs, bug fixing the compiler, keep working on windows support and some intermediate language changes for future releases. There were 119 commits since 0.25.1 by 24 contributors.

Language changes

Revert: Do not collapse unions for sibling types

In 0.25.0 we tried to improve the inferred type of unions of sibling types. Although it worked well for the compiler itself, some codebases out there exhibited some combinatorial explosion of unions due to this change. In 0.26.0, the change introduced in 0.25.0 is reverted. Read more at #6351.

Restrict instance variables initializer

When declaring instance variables it is sometimes handy to define an initial value:

class Counter
  @value = 0
end

When the expression is a constant or it does not depend on other instance variables the semantic is clear. Before 0.26.0, instance variables were allowed, but there were some corner issues regarding typing, semantics, and dependencies. So, from 0.26.0 instance variables are not allowed in the expression that determines the initial values of them. Class variables are still allowed. Inside initialize you are still allowed to assign instance variables between each other.

To illustrate why the semantics are not clear, there are rules that could allow the following code to evaluate to: 1, 2 or 3.

class Foo
  @bar = 0
  @baz = @bar + 1

  def initialize(@bar = 1)
    @bar = 2
  end

  def baz
    @baz
  end
end

Foo.new.baz # => ???

Wrapping and integer division operators

There are a new bunch of operators arriving in this version but, since crystal is written in crystal, in this version the only thing that is added are the parsing rules. In future versions semantics will be given, and later breaking changes will be introduced.

All this process is to allow, in a couple of versions, integer overflowing exceptions in arithmetics operations and integer division operators. This will empower safer and cleaner code.

Read more at #6329 and #6470.

There is a performance regression fixed in this release related to IO by #6304. Now, when buffered IO is used, the user can control independently if writes and reads are buffered or not.

You will find some great changes in HTTP::Server API for binding to different address.

A more fine grained method to support ssl is introduced in #5960. SSL can be toggled per binding instead of per server. So HTTP::Server#tls was dropped in favor of HTTP::Server#bind_ssl.

Another handy change introduced in #6500 is the addition of HTTP::Server#bind(URI|String) that infers protocol from scheme of the uri. This means that creating a server that in uses different kind of bindings is a piece of cake.

require "http/server"

server = HTTP::Server.new do |context|
  ...
end

server.bind "tcp://127.0.0.1:80"
server.bind "unix:///tmp/server.sock"
server.bind "ssl://127.0.0.1:443?key=private.key&cert=certificate.cert&ca=ca.crt"
server.listen

Windows support progress

The compiler and the stdlib is moving forward to support Windows.

Some of the cornerstones of the stdlib were ported:

Accessing environment information was added in #6333 and #6499.
File and Dir support has landed with #5623.
And supporting UTF-16 string messages in errors implemented in #6442

But definitely one of the most exciting additions in this version is the support of Windows structured exception handling (SEH). This was added in #6419 and collected work from many contributors and accomplish the extra mile to make things happen. To offer a bit of context information, although LLVM abstracts the target machine and architecture, there is a substantial difference on how to code exception handling in Windows vs. any other platform, if you are willing to dig intro LLVM you can read more about exception handling here.

Changelog format

This is the second release in which we are trying to improve the format of the changelog. It should be easier to read and depict changes in areas of interest. So, don’t miss the rest of the release changelog information with lots of valuable information.

Next step

Please update your Crystal and report any issues. If there are regression or blocking issues with 0.26.0, a 0.26.1 could be released earlier.

Thanks

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