changelog.md

1.2 - xxxx-xx-xx

Changes affecting backwards compatibility

Breaking changes in the standard library

• base64.encode no longer supports lineLen and newLine. Use base64.encodeMIME instead.
• os.splitPath() behavior synchronized with os.splitFile() to return "/" as the dir component of "/root_sub_dir" instead of the empty string.
• sequtils.zip now returns a sequence of anonymous tuples i.e. those tuples now do not have fields named "a" and "b".
• strutils.formatFloat with precision = 0 has the same behavior in all backends, and it is compatible with Python's behavior, e.g. formatFloat(3.14159, precision = 0) is now 3, not 3..
• Global variable lc has been removed from sugar.nim.
• distinctBase has been moved from sugar.nim to typetraits and now implemented as compiler type trait instead of macro. distinctBase in sugar module is now deprecated.
• CountTable.mget has been removed from tables.nim. It didn't work, and it was an oversight to be included in v1.0.
• tables.merge(CountTable, CountTable): CountTable has been removed. It didn't work well together with the existing inplace version of the same proc (tables.merge(var CountTable, CountTable)). It was an oversight to be included in v1.0.
• options now treats proc like other pointer types, meaning nil proc variables are converted to None.
• relativePath("foo", "foo") is now ".", not "", as "" means invalid path and shouldn't be conflated with "."; use -d:nimOldRelativePathBehavior to restore the old behavior
• joinPath(a,b) now honors trailing slashes in b (or a if b = "")
• times.parse now only uses input to compute its result, and not now: parse("2020", "YYYY", utc()) is now 2020-01-01T00:00:00Z instead of 2020-03-02T00:00:00Z if run on 03-02; it also doesn't crash anymore when used on 29th, 30th, 31st of each month.

Breaking changes in the compiler

• Implicit conversions for const behave correctly now, meaning that code like const SOMECONST = 0.int; procThatTakesInt32(SOMECONST) will be illegal now. Simply write const SOMECONST = 0 instead.
• The {.dynlib.} pragma is now required for exporting symbols when making shared objects on POSIX and macOS, which make it consistent with the behavior on Windows.
• The compiler is now more strict about type conversions concerning proc types: Type conversions cannot be used to hide .raise effects or side effects, instead a cast must be used. With the flag --useVersion:1.0 the old behaviour is emulated.

Library additions

• macros.newLit now works for ref object types.

• system.writeFile has been overloaded to also support openarray[byte].

• Added overloaded strformat.fmt macro that use specified characters as delimiter instead of '{' and '}'.

• introduced new procs in tables.nim: OrderedTable.pop, CountTable.del, CountTable.pop, Table.pop

• To strtabs.nim, added StringTable.clear overload that reuses the existing mode.

• Added browsers.osOpen const alias for the operating system specific "open" command.

• Added sugar.dup for turning in-place algorithms like sort and shuffle into operations that work on a copy of the data and return the mutated copy. As the existing sorted does.

• Added sugar.collect that does comprehension for seq/set/table collections.

• Added sugar.capture for capturing some local loop variables when creating a closure. This is an enhanced version of closureScope.

• Added typetraits.tupleLen to get number of elements of a tuple/type tuple, and typetraits.get to get the ith element of a type tuple.

• Added typetraits.genericParams to return a tuple of generic params from a generic instantiation

• Added os.normalizePathEnd for additional path sanitization.

• Added times.fromUnixFloat,toUnixFloat, subsecond resolution versions of fromUnix,toUnixFloat.

• Added wrapnils module for chains of field-access and indexing where the LHS can be nil. This simplifies code by reducing need for if-else branches around intermediate maybe nil values. E.g. echo ?.n.typ.kind

• Added minIndex, maxIndex and unzip to the sequtils module.

• Added os.isRelativeTo to tell whether a path is relative to another

• Added resetOutputFormatters to unittest

• Added expectIdent to the macros module.

• Added os.isValidFilename that returns true if filename argument is valid for crossplatform use.

• Added a with macro for easy function chaining that's available everywhere, there is no need to concern your APIs with returning the first argument to enable "chaining", instead use the dedicated macro with that was designed for it. For example:

type
  Foo = object
    col, pos: string

proc setColor(f: var Foo; r, g, b: int) = f.col = $(r, g, b)
proc setPosition(f: var Foo; x, y: float) = f.pos = $(x, y)

var f: Foo
with(f, setColor(2, 3, 4), setPosition(0.0, 1.0))
echo f

• Added times.isLeapDay
• Added a new module, std / compilesettings for querying the compiler about diverse configuration settings.

Library changes

• asyncdispatch.drain now properly takes into account selector.hasPendingOperations and only returns once all pending async operations are guaranteed to have completed.
• asyncdispatch.drain now consistently uses the passed timeout value for all iterations of the event loop, and not just the first iteration. This is more consistent with the other asyncdispatch apis, and allows asyncdispatch.drain to be more efficient.
• base64.encode and base64.decode was made faster by about 50%.
• htmlgen adds MathML support (ISO 40314).
• macros.eqIdent is now invariant to export markers and backtick quotes.
• htmlgen.html allows lang on the <html> tag and common valid attributes.
• macros.basename and basename= got support for PragmaExpr, so that an expression like MyEnum {.pure.} is handled correctly.
• httpclient.maxredirects changed from int to Natural, because negative values serve no purpose whatsoever.
• httpclient.newHttpClient and httpclient.newAsyncHttpClient added headers argument to set initial HTTP Headers, instead of a hardcoded empty newHttpHeader().
• parseutils.parseUntil has now a different behaviour if the until parameter is empty. This was required for intuitive behaviour of the strscans module (see bug #13605).

Language additions

• An align pragma can now be used for variables and object fields, similar to the alignas declaration modifier in C/C++.

• =sink type bound operator is now optional. Compiler can now use combination of =destroy and copyMem to move objects efficiently.

Language changes

• Unsigned integer operators have been fixed to allow promotion of the first operand.
• Conversions to unsigned integers are unchecked at runtime, imitating earlier Nim versions. The documentation was improved to acknowledge this special case. See nim-lang/RFCs#175 for more details.

Tool changes

• Fix Nimpretty must not accept negative indentation argument because breaks file.

Compiler changes

• JS target indent is all spaces, instead of mixed spaces and tabs, for generated JavaScript.
• The Nim compiler now supports the --asm command option for easier inspection of the produced assembler code.
• The Nim compiler now supports a new pragma called .localPassc to pass specific compiler options to the C(++) backend for the C(++) file that was produced from the current Nim module.
• The compiler now inferes "sink parameters". To disable this for a specific routine, annotate it with .nosinks. To disable it for a section of code, use {.push sinkInference: off.}...{.pop.}.
• The compiler now supports a new switch --panics:on that turns runtime errors like IndexError or OverflowError into fatal errors that cannot be caught via Nim's try statement. --panics:on can improve the runtime efficiency and code size of your program significantly.
• The compiler now warns about inheriting directly from system.Exception as this is very bad style. You should inherit from ValueError, IOError, OSError or from a different specific exception type that inherits from CatchableError and cannot be confused with a Defect.

Bugfixes

• The FD variant of selector.unregister for ioselector_epoll and ioselector_select now properly handle the Event.User select event type.
• joinPath path normalization when / is the first argument works correctly: assert "/" / "/a" == "/a". Fixed the edgecase: assert "" / "" == "".
• xmltree now adds indentation consistently to child nodes for any number of children nodes.