Nim/changelog.md

v1.8.x - yyyy-mm-dd

Changes affecting backward compatibility

• Optional parameters in combination with : body syntax (RFC #405) are now opt-in via experimental:flexibleOptionalParams.

Standard library additions and changes

Standard library additions and changes

• macros.parseExpr and macros.parseStmt now accept an optional filename argument for more informative errors.
• Module colors expanded with missing colors from the CSS color standard.
• Fixed lists.SinglyLinkedList being broken after removing the last node (#19353).

Language changes

• Pragma macros on type definitions can now return nnkTypeSection nodes as well as nnkTypeDef, allowing multiple type definitions to be injected in place of the original type definition.

  import macros

  macro multiply(amount: static int, s: untyped): untyped =
    let name = $s[0].basename
    result = newNimNode(nnkTypeSection)
    for i in 1 .. amount:
      result.add(newTree(nnkTypeDef, ident(name & $i), s[1], s[2]))

  type
    Foo = object
    Bar {.multiply: 3.} = object
      x, y, z: int
    Baz = object

  # becomes

  type
    Foo = object
    Bar1 = object
      x, y, z: int
    Bar2 = object
      x, y, z: int
    Bar3 = object
      x, y, z: int
    Baz = object

• Case statement macros are no longer experimental, meaning you no longer need to enable the experimental switch caseStmtMacros to use them.

Compiler changes

• nim can now compile version 1.4.0 as follows: nim c --lib:lib --stylecheck:off compiler/nim, without requiring -d:nimVersion140 which is now a noop.

• --styleCheck now only applies to the current package.

Tool changes

• The gc switch has been renamed to mm ("memory management") in order to reflect the reality better. (Nim moved away from all techniques based on "tracing".)

• Nim now supports Nimble version 0.14 which added support for lock-files. This is done by a simple configuration change setting that you can do yourself too. In $nim/config/nim.cfg replace pkgs by pkgs2.

• There is a new switch --nimMainPrefix:prefix to influence the NimMain that the compiler produces. This is particularly useful for generating static libraries.