Open Dylan 2016.1 Release Notes


This document describes the 2016.1 release of Open Dylan, released XXX XX, 2016.

Dylan Standard Library

  • Symbol comparisons when using \= are now the same as using \== rather than being significantly more expensive. See issue #899.
  • The function dispatch implementation now makes a proper distinction between <single-method-engine-node> and <keyword-method> with the help of a new primitive-callable-as-engine-node? compiler primitive.


The LLVM back-end, which uses LLVM 7.x or later for code generation, is now full-featured and mature on i386 and x86_64 Linux, FreeBSD, and macOS platforms. Features of the LLVM back-end include:

  • Full source-level debug information
  • Zero-cost nonlocal exit support
  • Arithmetic exception handling

Build System

  • The arguments to configure for specifying which garbage collector to use have changed (again). The arguments are now:


    The with-mps option (for pointing to the Memory Pool System source directory) is only needed when using the MPS collector with the HARP back-end on either 32-bit x86 FreeBSD or 32-bit x86 Linux. The system should be able to find the Boehm-Demers-Weiser collector automatically if it is in the standard system install directory; the with-gc option should only be needed if it is installed in a non-standard location.

    The default collectors are MPS for the HARP back-end’s run-time library, and the Boehm-Demers-Weiser collector for the C and LLVM back-ends. These shouldn’t be changed unless you’re sure you know what you’re doing.

  • A new option for building C++ code, c++-source-files, has been added to LID files. This matches the c-source-files: keyword.


  • Nested C structs by value are now supported by the C backend. Previously, using this construct would result in a compilation error in the generated C code.

  • Using %call-c-function or %objc-msgsend with a void result type no longer requires specifying a result type of <raw-c-void>. Simply putting an empty value list is sufficient:

    %call-c-function ("SetLastError", c-modifiers: "__stdcall")
        (dwErrorCode :: <raw-c-unsigned-long>) => ()

    Previously, this required specifying the result type explicitly:

    %call-c-function ("SetLastError", c-modifiers: "__stdcall")
        (dwErrorCode :: <raw-c-unsigned-long>) => (nothing :: <raw-c-void>)


  • The bit-count operation from bit-vector (also used by <bit-set>) has been changed to use the new primitive-machine-word-count-ones that has been added in this release.


Common Dylan

  • The transcendentals module now has a sincos generic function.
  • The transcendentals module now has a hypot generic function.
  • The transcendentals module now has an ilog2 function that returns the integer value of the logarithm of a value in base 2.
  • The transcendental and hyperbolic functions are no longer sealing their domains on <real> parameters.
  • Again in the transcendentals module, many methods have been removed that converted from <real> to <float>. Callers should pass in values of the appropriate type and precision instead. This impacts:
    • ^, exp, log
    • sqrt
    • sin, cos, tan
    • asin, acos, atan
    • sinh, cosh, tanh
    • asinh, acosh, atanh
  • The common-dylan library now provides a classify-float method which will return if the given float is #"normal", #"zero", #"infinite", #"nan", or #"subnormal".
  • The common-dylan library now provides hexstring and from-hexstring methods for fast conversion from and to hexadecimal strings.
  • The thread module has gained a current-thread-id function. The thread-id is also available for any <thread> object.
  • The simple-profiling module now exports start-profiling and stop-profiling rather than requiring that users directly invoke start-profiling-type and stop-profiling-type multiple times.
  • The machine-words module now knows how to count the bits set in a machine word via %count-ones. This is also available as a new compiler primitive, primitive-machine-word-count-ones.
  • Mismatches in the use of internal-use raw types have been resolved.


  • The compiler emits warnings for issues with define sealed domain:

    • Incorrect number of type specializers provided. The number of type specializers must match the number of required parameters for the generic function.

    • Type specializers are not subtypes of the corresponding required argument of the generic function.

      For example, this is useful for catching an incorrect sealing of make:

      define sealed domain make (<my-class>); // Wrong
      define sealed domain make (singleton(<my-class>)); // Correct
    • Previously, define domain was accepted without warning. This is not valid Dylan syntax as it should be define sealed domain.

  • Dylan functions that are marked as not-inline now take that into account when generating code in the LLVM and C back-ends.

  • The C back-end no longer generates invalid C when outputting a float with a value of infinity or NaN.

  • Some bugs that didn’t permit valid floating point literals to be used have been fixed. These are typically edge cases like +.5 or -3d3 rather than commonly used literal notations.

  • The C back-end correctly handles indirect C-functions (where a function pointer is given to be invoked rather than a direct function call).

  • Warnings and errors are now colorized when printing on supporting output devices.

  • The compiler progress messages are now less verbose unless the -verbose command-line option is supplied.

  • Warnings that refer to primitive and C functions are now clearer.

  • A bug in the C back-end that broke required return values combined with type-checked #rest return values has been fixed.

  • An erroneous validity check for the Base-Address: keyword in LID or HDP project files on Windows has been fixed.

  • The HARP back-end can now handle raw FFI calls that return <raw-single-float> or <raw-double-float> values.

  • The compiler command line, as well as the interactive build and link commands, accept a -jobs option to control the number of concurrent external build processes during the link stage. Setting this to the number of available CPU cores can provide speedups for large builds.


  • There is a new dylan-lldb wrapper script which can be used to launch lldb and pre-load the Open Dylan LLDB integration scripts. lldb is the debugger that is part of the LLVM project. It is the default debugger on macOS.

    If you need it to launch a custom build of LLDB, you can set the OPEN_DYLAN_LLDB environment variable to point to an alternative lldb executable.


  • The documentation generator included within the compiler has been updated to produce better and more accurate documentation that will require less manual editing. To use it, after compiling your library, use this command:

    export -format rst -file my-lib.rst interface-reference


  • An implementation of indenting streams for handling indented text output has been added. See <indented-stream>, indent, and with-indentation in the streams module.
  • Some generic functions that apply to <buffered-stream> have had their signatures tightened.
  • Mismatches in the use of internal-use raw types have been resolved.


  • Support for printing a backtrace (with demangled Dylan function names) when an unhandled error condition is signaled has been implemented. Note that this requires the use of the optional libunwind library.

  • Support for handling “invalid” floating point exceptions has been added. These are generated when taking the square root of a negative number and other similar situations where the numerical domain is invalid.

    When an invalid floating point exception occurs, <arithmetic-domain-error> will be signaled (much like the other <arithmetic-error> situations).

  • Limited integer instance checks have been optimized. This will have the most impact when using the LLVM compiler backend.

  • In the C runtime, the primitive_sleep now functions correctly.

  • Two new primitives, primitive-read-cycle-counter and primitive-read-return-address, have been added. These are useful for writing profiling and event logging tools.


  • New specializations on as have been added for creating locators from strings for the <file-system-directory-locator> and <file-system-file-locator> classes. These aren’t typically used but their omission led to possible confusion for users.
  • A problem with constructing <date> objects for time_t values with more than 30 bits (i.e., any time after Sat Jan 10 13:37:04 UTC 2004) has been fixed.
  • Mismatches in the use of internal-use raw types have been resolved.