0.20.3

• (breaking change) IO#gets, IO#each_line, String#lines, String#each_line, etc. now chomp lines by default. You can pass chomp: false to prevent automatic chomping. Note that chomp is true by default for argless IO#gets (read line) but false if args are given.
• (breaking change) HTTP::Handler is now a module instead of a class (thanks @andrewhamon)
• (breaking change) Free variables now must be specified with forall, a single uppercase letter will not work anymore
• (breaking change) The libs directory is no longer in the default CRYSTAL_PATH, use lib (running crystal deps should fix this)
• Optimized compile times, specially on linux
• private can now be used with macros inside types (thanks @makenowjust)
• CLI: the -s/--stats option now also shows execution time (thanks @makenowjust)
• CLI: added -t/--time to show execution time (thanks @makenowjust)
• Socket now allows any family/type/protocol association, and many other improvements (thanks @ysbaddaden)
• YAML: an IO can now be passed to from_yaml (thanks @makenowjust)
• Added class_getter, class_setter, class_property, etc. (thanks @Sija)
• Added String#lchomp (thanks @Sija)
• Added IO#read_fully?
• Added Iterator#flatten (thanks @makenowjust)
• Added HTTP::WebSocket#ping, pong, on_ping, on_pong, and now a ping message is automatically replied with a pong message (thanks @Sija)
• Added File#empty? and Dir#empty? (thanks @dylandrop)
• Added Time::Span#/(Time::Span) (thanks @RX14)
• Added String#split versions that accept a block (thanks @splattael)
• Added URI#normalize and normalize! (thanks @taylorfinnell)
• Added reuse optional argument to many Array, Enumerable and Iterable methods that allow you to reuse the yielded/return array for better performance and less memory footprint
• The :debug flag is now present when compiled with --debug, useful for doing flag?(:debug) in macros (thanks @luislavena)
• Many bug fixes and performance improvements

0.20.1

• (breaking change) Set#merge as renamed to Set#merge!
• (breaking change) Slice.new(size) no longer works with non primitive integers and floats
• (breaking change) The macro method argify was renamed to splat
• Added pretty printing. The methods p and pp now use it. To get the old behaviour use puts obj.inspect
• Added ArrayLiteral#[]=, TypeNode#constant, TypeNode#overrides? and HashLiteral#double_splat in macros
• Added a finished macro hook that runs at the end of the program
• Added support for declaring the type of a local variable
• Added Slice.empty
• Flags enums now have a none? method
• IO::ByteFormat has now methods to encode/decode to/from a Slice
• Spec: the line number passed to run a specific it block can now be inside any line of that block
• The CallConvention attribute can now also be applied to a lib declaration, and all funs inside it will inherit it
• The method_missing hook can now define a method, useful for specifying block arguments
• Support double splat in macros ({{**...}})
• Some bug fixes

0.20.0

• (breaking change) Removed ifdef from the language
• (breaking change) Removed PointerIO
• (breaking change) The body property of HTTP::Request is now an IO? (previously it was String). Use request.body.try(&.gets_to_end) if you need the entire body as a String.
• (breaking change) MemoryIO has been renamed to IO::Memory. The old name can still be used but will produce a compile-time warning. MemoryIO will be removed immediately after 0.20.0.
• (breaking change) Char#digit? was split into Char#ascii_number? and Char#number?. The old name is still available and will produce a compile-time warning, but will be removed immediately after 0.20.0.
• (breaking change) Char#alpha? was split into Char#ascii_letter? and Char#letter?. The old name is still available and will produce a compile-time warning, but will be removed immediately after 0.20.0.
• (breaking change) The Iterable module is now generic
• Many String and Char methods are now unicode-aware, for example String#downcase, String#upcase, Char#downcase, Char#upcase, Char#whitespace?, etc.
• Added support for HTTP client and server streaming.
• Added support for ARM (thanks @ysbaddaden)
• Added support for AArch64 (thanks @ysbaddaden)
• Added support for LLVM 3.9 (thanks @ysbaddaden)
• Added __END_LINE__ magic constant in method default arguments: will be the last line of a call (if the call has a block, it will be the last line of that block)
• Added @def inside macros that takes the value of the current method
• API docs have a nicer style now, and notes like TODO and DEPRECATED are better highlighted (thanks @samueleaton)
• Slight improvement to debugging support (thanks @ggiraldez)
• Line numbers in backtraces (linux only for now) (thanks @ysbaddaden)
• Added iteration times to Benchmark.ips (thanks @RX14)
• Allow HTTP::Client block initializer to be used when passing an URI (thanks @philnash)
• JSON.mapping and YAML.mapping getter/setter generation can now be controlled (thanks @zatherz)
• Time is now serializable to JSON and YAML using ISO 8601 date-time format
• Added IO::MultiWriter (thanks @RX14)
• Added String#index(Regex) and String#rindex(Regex) (thanks @zatherz)
• Added String#partition and String#rpartition (thanks @johnjansen)
• Added FileUtils.cd, FileUtils.mkdir, FileUtils.mkdir_p, FileUtils.mv, FileUtils.pwd, FileUtils.rm, FileUtils.rm_r, FileUtils.rmdir (thanks @ghivert)
• Added JSON::Builder#raw_field (thanks @kostya)
• Added Enumerable#chunks and Iterator#chunk (thanks @kostya)
• Added Iterator#with_index
• Several enhancements to the Random module: now works for any integer type and avoids overflows (thanks @BlaXpirit)
• Optimized Array#sort by using introsort (thanks @c910335)
• Several bug fixes

0.19.4

• Added support for OpenBSD (thanks @wmoxam and @ysbaddaden)
• More iconv fixes for FreeBSD (thanks @ysbaddaden)
• Changed how require works for the upcoming shards release (this is backwards compatible). See #2788
• Added Atomic and exposed all LLVM atomic instructions to Crystal (needed to implemented multiple-thread support)
• Added Process.executable_path (thanks @kostya, @whereami and @ysbaddaden)
• Added HTML.unescape (thanks @dukex)
• Added Char#+(Int) and Char#-(Int)
• A few bug fixes

0.19.3

• crystal eval now accepts some flags like --stats, --release and --help
• Added File.chown and File.chmod (thanks @ysbaddaden)
• Added Time::Span.zero (useful for doing sum) (thanks @RX14)
• Added docs to OAuth and OAuth2
• Several bug fixes

0.19.2

• Generic type variables no longer need to be single-letter names (for example class Gen(Foo) is now possible)
• Added syntax to denote free variables: def foo(x : T) forall T. The old rule of single-letter name still applies but will be removed in the future.
• Removed the restriction that top-level types and constants can't have single-letter names
• Added @[Extern] attribute to mark regular Crystal structs as being able to be used in C bindings
• Faster Char#to_s when it's ASCII: this improves the performance of JSON and CSV parsing
• crystal spec: allow passing --release and other options
• crystal spec: allow running all specs in a given directory
• crystal playground: support custom workbook resources (thanks @bcardiff)
• crystal playground: standard output now understands ANSI colors (thanks @bcardiff)
• Added many more macro methods to traverse AST nodes (thanks @BlaXpirit)
• Error messages no longer include a type trace by default, pass --error-trace to show the full trace (the trace is often useless and makes it harder to understand error messages)
• Several bug fixes

0.19.1

• Types (class, module, etc.) can now be marked as private.
• Added WeakRef (thanks @bcardiff)
• Several bug fixes

0.19.0

• (breaking change) Added select keyword
• (breaking change) Removed $global variables. Use @@Class variables instead.
• (breaking change) Heredoc now ends when the matching identifier is found, either followed by a space or by a non-identifier
• (breaking change) Assignment to a local variable inside an assignment to that same variable is now an error
• (breaking change) Type names like T, T1, U, etc., are now disallowed at the top level, to avoid conflicts with free variables
• (breaking change) Type lookup (Foo::Bar::Baz) had some incorrect behaviour that now is fixed. This can break existing code that relied on this incorrect behaviour. The fix is to fully qualify types (::Foo::Bar::Baz)
• (breaking change) In relationships like class Bar < Foo(Baz) and include Moo(Baz), all of Foo, Moo and Baz must be defined before that point (this was not always the case in previous versions)
• (breaking change) Removed the deprecated syntax x as T
• (breaking change) Removed block form of String#match
• (breaking change) Removed IO#read_nonblock
• (breaking change) Int#/ now performs floored division. Use Int#tdiv for truncated division (see their docs to learn the difference)
• Added support for LLVM 3.8 (thanks @omarroth)
• || now does type filtering
• Generic inheritance should now work well, and (instantiated) generic modules can now be used as the type of instance variables
• NamedTuple can now be accessed with strings too (thanks @jhass)
• Base64 can now encode and decode directly to an IO (thanks @kostya)
• BigInt now uses GMP implementation of gcd and lcm (thanks @endSly)
• ECR now supports removing leading and trailing whitespace (<%-, -%>)
• HTTP::Request#path now never returns nil: it fallbacks to "/" (thanks @jhass)
• String#tr(..., "") is now the same as String#delete
• tool hierarchy now supports --format json (thanks @bmulvihill)
• Added Char#ascii?
• Added Class#nilable? and Union#nilable?
• Added Hash#has_value? (thanks @kachick)
• Added IO::Sized and IO::Delimited (thanks @RX14)
• Added IO::Hexdump (thanks @ysbaddaden)
• Added IO#noecho and IO#noecho! (thanks @jhass)
• Added Logger.new(nil) to create a null logger
• Added OptionParser#missing_option and OptionParser#invalid_option (thanks @jhass)
• Added Process.exists?, Process#exists? and Process#terminated? (thanks @jhass)
• Added Process.exec (thanks @jhass)
• Added Slice#copy_to, Slice#copy_from, Slice#move_to and Slice#move_from (thanks @RX14)
• Added URI#== and URI#hash (thanks @timcraft)
• Added YAML#parse(IO)
• Added Indexable module that Array, Slice, Tuple and StaticArray include
• Added indent parameter to to_pretty_json
• Added lazy form of getter and property macros
• Added macro methods to access an ASTNode's location
• Unified String and Char to integer/float conversion API (thanks @jhass)
• Lots of bug fixes

0.18.7

• The compile command was renamed back to build. The compile command is deprecated and will be removed in a future version
• Fibers now can be spawned with a name
• ECR macros can now be required with just require "ecr"
• Several bugs fixes and enhancements

0.18.6

0.18.6 (28-06-2016)

• T? is now parsed as Union(T, Nil) outside the type grammar
• Added String#sub overloads for replacing an index or range with a char or string
• Several bugs fixes

0.18.5 (27-06-2016)

• Added OpenSSL::SSL::Socket#alpn_protocol
• Added IO#copy(src, desc, limit) (thanks @jreinert)
• Added TypeNode#instance macro method
• Several bugs fixes