Nim/changelog.md

v0.19.X - XX/XX/2018

Changes affecting backwards compatibility

• The stdlib module future has been renamed to sugar.
• macros.callsite is now deprecated. Since the introduction of varargs parameters this became unnecessary.
• Anonymous tuples with a single element can now be written as (1,) with a trailing comma. The underlying AST is nnkTupleConst(newLit 1) for this example. nnkTupleConstr is a new node kind your macros need to be able to deal with!
• Indexing into a cstring for the JS target is now mapped to charCodeAt.
• Assignments that would "slice" an object into its supertype are now prevented at runtime. Use ref object with inheritance rather than object with inheritance to prevent this issue.
• The not nil type annotation now has to be enabled explicitly via {.experimental: "notnil"} as we are still not pleased with how this feature works with Nim's containers.
• The parser now warns about inconsistent spacing around binary operators as these can easily be confused with unary operators. This warning will likely become an error in the future.

Breaking changes in the standard library

• re.split for empty regular expressions now yields every character in the string which is what other programming languages chose to do.

• The returned tuple of system.instantiationInfo now has a third field containing the column of the instantiation.

• ``cookies.setCookie` no longer assumes UTC for the expiration date.

• strutils.formatEng does not distinguish between nil and "" strings anymore for its unit parameter. Instead the space is controlled by a new parameter useUnitSpace.

• proc `-`*(a, b: Time): int64 in the times module has changed return type to times.Duration in order to support higher time resolutions. The proc is no longer deprecated.

• posix.Timeval.tv_sec has changed type to posix.Time.

Breaking changes in the compiler

• The undocumented #? braces parsing mode was removed.
• The undocumented PHP backend was removed.

Library additions

• re.split now also supports the maxsplit parameter for consistency with strutils.split.
• Added system.toOpenArray in order to support zero-copy slicing operations. This is currently not yet available for the JavaScript target.
• Added getCurrentDir, findExe, cpDir and mvDir procs to nimscript.
• The times module now supports up to nanosecond time resolution when available.
• Added the type times.Duration for representing fixed durations of time.
• Added the proc times.convert for converting between different time units, e.g days to seconds.

Library changes

• macros.astGenRepr, macros.lispRepr and macros.treeRepr now escapes the content of string literals consistently.
• macros.NimSym and macros.NimIdent is now deprecated in favor of the more general NimNode.
• macros.getImpl now includes the pragmas of types, instead of omitting them.
• macros.hasCustomPragma and macros.getCustomPragmaVal now also support ref and ptr types, pragmas on types and variant fields.
• system.SomeReal is now called SomeFloat for consistency and correctness.
• algorithm.smartBinarySearch and algorithm.binarySearch is now joined in binarySearch. smartbinarySearch is now deprecated.
• The terminal module now exports additional procs for generating ANSI color codes as strings.

Language additions

• Dot calls combined with explicit generic instantiations can now be written as x.y[:z]. x.y[:z] that is transformed into y[z](x) in the parser.
• func is now an alias for proc {.noSideEffect.}.
• In order to make for loops and iterators more flexible to use Nim now supports so called "for-loop macros". See the manual <manual.html#macros-for-loop-macros>_ for more details.

Language changes

• The importcpp pragma now allows importing the listed fields of generic C++ types. Support for numeric parameters have also been added through the use of static[T] types. (#6415)

• Native C++ exceptions can now be imported with importcpp pragma. Imported exceptions can be raised and caught just like Nim exceptions. More details in language manual.

• nil for strings/seqs is finally gone. Instead the default value for these is "" / @[].

• Accessing the binary zero terminator in Nim's native strings is now invalid. Internally a Nim string still has the trailing zero for zero-copy interoperability with cstring. Compile your code with the new switch --laxStrings:on if you need a transition period.

• The command syntax now supports keyword arguments after the first comma.

• Thread-local variables can now be declared inside procs. This implies all the effects of the global pragma.

• Nim now supports except clause in the export statement.

Tool changes

• jsondoc2 has been renamed jsondoc, similar to how doc2 was renamed doc. The old jsondoc can still be invoked with jsondoc0.

Compiler changes

• The VM's instruction count limit was raised to 1 billion instructions in order to support more complex computations at compile-time.

• Support for hot code reloading has been implemented for the JavaScript target. To use it, compile your code with --hotCodeReloading:on and use a helper library such as LiveReload or BrowserSync.

• A new compiler option --cppCompileToNamespace puts the generated C++ code into the namespace "Nim" in order to avoid naming conflicts with existing C++ code. This is done for all Nim code - internal and exported.

• Added macros.getProjectPath and ospaths.putEnv procs to Nim's virtual machine.

• The deadCodeElim option is now always turned on and the switch has no effect anymore, but is recognized for backwards compatibility.

• experimental is now a pragma / command line switch that can enable specific language extensions, it is not an all-or-nothing switch anymore.

Bugfixes