Nim/changelogs/changelog_0_19_0.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 nnkTupleConstr(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.
• The 'c and 'C' suffix for octal literals is now deprecated to bring the language in line with the standard library (e.g. parseOct).
• The dot style for import paths (e.g import path.to.module instead of import path/to/module) has been deprecated.

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.

• The times.parse and times.format procs have been rewritten. The proc signatures are the same so it should generally not break anything. However, the new implementation is a bit stricter, which is a breaking change. For example parse("2017-01-01 foo", "yyyy-MM-dd") will now raise an error.

• 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.

• The times.Timezone is now an immutable ref-type that must be initialized with an explicit constructor (newTimezone).

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

• math.`mod` for floats now behaves the same as mod for integers (previously it used floor division like Python). Use math.floorMod for the old behavior.

• For string inputs, unicode.isUpper and unicode.isLower now require a second mandatory parameter skipNonAlpha.

• For string inputs, strutils.isUpperAscii and strutils.isLowerAscii now require a second mandatory parameter skipNonAlpha.

• osLastError is now marked with sideEffect

• The procs parseHexInt and parseOctInt now fail on empty strings and strings containing only valid prefixes, e.g. "0x" for hex integers.

• terminal.setCursorPos and terminal.setCursorXPos now work correctly with 0-based coordinates on POSIX (previously, you needed to use 1-based coordinates on POSIX for correct behaviour; the Windows behaviour was always correct).

• lineInfoObj now returns absolute path instead of project path. It's used by lineInfo, check, expect, require, etc.

• net.sendTo no longer returns an int and now raises an OSError.

• threadpool's await and derivatives have been renamed to blockUntil to avoid confusions with await from the async macro.

Breaking changes in the compiler

• The undocumented #? braces parsing mode was removed.
• The undocumented PHP backend was removed.
• The default location of nimcache for the native code targets was changed. Read the compiler user guide for more information.

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.
• Added the proc algorithm.binarySearch[T, K] with the cmp parameter.
• Added the proc algorithm.upperBound.
• Added inverse hyperbolic functions, math.arcsinh, math.arccosh and math.arctanh procs.
• Added cotangent, secant and cosecant procs math.cot, math.sec and math.csc; and their hyperbolic, inverse and inverse hyperbolic functions, math.coth, math.sech, math.csch, math.arccot, math.arcsec, math.arccsc, math.arccoth, math.arcsech and math.arccsch procs.
• Added the procs math.floorMod and math.floorDiv for floor based integer division.
• Added the procs rationals.`div,rationals.mod`,rationals.floorDivandrationals.floorMod`` for rationals.
• Added the proc math.prod for product of elements in openArray.
• Added the proc parseBinInt to parse a binary integer from a string, which returns the value.
• parseOct and parseBin in parseutils now also support the maxLen argument similar to parseHexInt.
• Added the proc flush for memory mapped files.
• Added the MemMapFileStream.
• Added a simple interpreting event parser template eventParser to the pegs module.
• Added macros.copyLineInfo to copy lineInfo from other node.
• Added system.ashr an arithmetic right shift for integers.

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.
• Added the parameter val for the CritBitTree[int].inc proc.
• An exception raised from a test block of unittest now shows its type in error message.
• The compiler/nimeval API was rewritten to simplify the "compiler as an API". Using the Nim compiler and its VM as a scripting engine has never been easier. See tests/compilerapi/tcompilerapi.nim for an example of how to use the Nim VM in a native Nim application.
• Added the parameter val for the CritBitTree[T].incl proc.
• The proc tgamma was renamed to gamma. tgamma is deprecated.
• The pegs module now exports getters for the fields of its Peg and NonTerminal object types. Pegs with child nodes now have the standard items and pairs iterators.
• The accept socket procedure defined in the net module can now accept a nil socket.

Language additions

• Dot calls combined with explicit generic instantiations can now be written as x.y[:z] which is transformed into y[z](x) by 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 for more details. This feature enables a Python-like generic enumerate implementation.

• Case statements can now be rewritten via macros. See the manual for more information. This feature enables custom pattern matchers.

• the typedesc special type has been renamed to just type.

• static and type are now also modifiers similar to ref and ptr. They denote the special types static[T] and type[T].

• Forcing compile-time evaluation with static now supports specifying the desired target type (as a concrete type or as a type class)

• The type operator now supports checking that the supplied expression matches an expected type constraint.

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 "" / @[]. Use --nilseqs:on for a transition period.

• 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 the except clause in the export statement.

• Range float types, example range[0.0 .. Inf]. More details in language manual.

• The {.this.} pragma has been deprecated. It never worked within generics and we found the resulting code harder to read than the more explicit obj.field syntax.

• "Memory regions" for pointer types have been deprecated, they were hardly used anywhere. Note that this has nothing to do with the --gc:regions switch of managing memory.

• The exception hierarchy was slightly reworked, SystemError was renamed to CatchableError and is the new base class for any exception that is guaranteed to be catchable. This change should have minimal impact on most existing Nim code.

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 3 million 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 os.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.

• Nintendo Switch was added as a new platform target. See the compiler user guide for more info.

• macros.bindSym now capable to accepts not only literal string or string constant expression. bindSym enhancement make it also can accepts computed string or ident node inside macros / compile time functions / static blocks. Only in templates / regular code it retains it's old behavior. This new feature can be accessed via {.experimental: "dynamicBindSym".} pragma/switch.

• On Posix systems the global system wide configuration is now put under /etc/nim/nim.cfg, it used to be /etc/nim.cfg. Usually it does not exist, however.

• On Posix systems the user configuration is now looked under $XDG_CONFIG_HOME/nim/nim.cfg (if XDG_CONFIG_HOME is not defined, then under ~/.config/nim/nim.cfg). It used to be $XDG_CONFIG_DIR/nim.cfg (and ~/.config/nim.cfg).

Similarly, on Windows, the user configuration is now looked under %APPDATA%/nim/nim.cfg. This used to be %APPDATA%/nim.cfg.

Bugfixes