Open Dylan 2014.1 Release Notes


This document describes the 2014.1 release of Open Dylan, released December 29, 2014.

Bash Completion

A bash completion script is now included for dylan-compiler and can be found in share/opendylan/bash_completion/. This can be symlinked into the relevant bash_completion.d directory on your system.

Build System

  • The Jam files for Linux, FreeBSD and OS X have been updated to support doing a build when there are spaces in the path to the current working directory. This was previously only handled correctly for Windows.

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


    If the GC is Boehm and it is installed system-wide, then the with-gc-path parameter should not be needed. It is always necessary for MPS and is needed for Boehm if Boehm is installed into a non-standard location.

  • When running make, performing a full bootstrap is now the default action. This was pretty much required before and was a common source of confusion, especially when preparing to install a development build.

  • A bug introduced in 2013.2 that broke the handling of jam-includes has been fixed.

  • Build scripts have moved. Previously, they were installed in the lib directory. They are now installed in a share/opendylan/build-scripts/ directory.


  • The intermediate language of the compiler, named Dylan Flow Machine, has been instrumented with tracing facilities. Changes to the control and data flow, as well as optimization information, can be received by setting the *trace-dfm-callback* (exported from the dfmc-flow-graph) variable to a unary function. The variable *trace-dfm-outputter* should also be set (structured-output, exported from the dfmc-debug-back-end library might be useful).

    The argument to the *trace-dfm-callback itself is a property list containing at least a type key, a source location (method, file, library keys), likely a nodeid key, and various other information.

    Compiling the dylan library with tracing emits lots of data (250MB). Therefore, a filtering can be established on a file name, method name, and/or library name. The variables *trace-dfm-library*, *trace-dfm-file*, and *trace-dfm-method* are of type false-or(<symbol>) and are exported from the dfmc-flow-graph library.

    An example user of this interface is on GitHub. A screencast showing an earlier implementation of this optimization visualization can be seen here.

  • The C back-end would emit character constants that current versions of clang considered an error. The C back-end now generates a better representation.

  • The output of dylan-compiler is less verbose by default. Use the -verbose flag to get the old behavior.

  • Some extensions to the Dylan language that have been present in the Open Dylan compiler for a long time have been documented, including extensions to the macro system and an alternative syntax for currying functions.


  • There is a new objc-selector-definer compiler macro. This supports the Objective C / Dylan bridge by allowing the definition of Objective C selectors and functions for sending them, complete with type information.

    An example usage from the Objective C / Dylan bridge library is:

    define objc-selector sel/alloc
      parameter target :: <objc/class>;
      result objc-instance :: <objc/instance-address>;
      selector: "alloc";

    This must be used in conjunction with the Objective C / Dylan bridge library.

  • A result of a C-function may now be flagged as an error-result which means that the import function will be called, but the actual value will not be returned. This is useful for wrapping C APIs which return error codes that should signal conditions when an error occurs.

  • New C-FFI types, <C-size-t> and <C-ssize-t> are available. These map to the underlying C types size_t and ssize_t.

  • Passing structs by value to C functions when using the C back-end has been fixed. This was not broken when using the HARP back-end.

C Run-time

  • debug-message no longer crashes when printing some conditions.

Common Dylan

  • The simple-io module has been renamed to simple-format. A convenience module that re-exports simple-format has been left as simple-io for short term compatibility.
  • The format-to-string function has been moved to the newly renamed simple-format module. This function is no longer exported from common-extensions. You no longer need to exclude this function from common-dylan or common-extensions if you use the format module from the io library.
  • The <timer> class has been renamed to <profiling-timer>.
  • The function integer-to-string is now faster.
  • On Mac OS X, application-filename() now returns the full absolute path. It also handles symlinks correctly now. This means that a symlink to a Dylan executable will function correctly as it already did on Linux and FreeBSD.
  • The routine used for printing function signatures when displaying an error / condition now shows a more accurate signature rather than only the function specializers.


  • When using LLDB for debugging, Dylan support is now available. To use this, you need to import the Python scripts:

    command script import /path/to/opendylan/share/opendylan/lldb/dylan

    Do not import the scripts under that directory directly. Once this has been loaded, then commands like frame variable will automatically start showing Dylan values:

    (lldb) frame variable
    (dylan_value) mepargs_ = 0xbfffd4c0 {<simple-object-vector>: size: 2} {
      [0] = 0x00000009 {<integer>: 2}
      [1] = 0x02861eb0 {<byte-char-file-stream>}
    (dylan_value) e_ = 0x0018a288 {<absent-engine-node>}
    (dylan_value) parent_ = 0x005cc384 {<incremental-generic-function>: do-execute-command}
    (dylan_value) T3 = 0x00000000 {}


  • dfmc-execution provides a framework for interpreting the compiler’s IR (DFM). It has been experimentally restored from the source control history and some basic tests have been created in sources/dfmc/testing/. It currently has many limitations and bugs which we are still working out.
  • We are evaluating using dfmc-execution to replace or augment the capabilities of ^top-level-eval-using-optimization in dfmc-conversion.
  • We are interested in hearing what sort of things people may be interested in using this for.


  • There is now an specialized implementation of member? defined for searching for a <byte-character> in a <byte-string>.


  • Much like %call-c-function for low-level C-FFI, there is now a %objc-msgsend for low-level Objective C messaging integration. More information about this will be forthcoming in an objc-dylan bridge library.

    %objc-msgsend takes the target and selector as <raw-machine-word> values. As with %call-c-function, all values passed in and returned should be raw values.

    If you need the objc_msgSend_stret or other variants, pass c-modifiers: "_stret" or similar after the selector. The value passed here will be appended to objc_msgSend so it works for all variants, including sending to the super (objc_msgSendSuper, etc).

    %objc-msgsend (target, selector)
       (argument :: <raw-type>)
     => ()


  • A crash resulting from memory corruption when using sha-1 has been fixed.
  • The library now builds on Windows.


  • New functions format-err and force-err have been added that do the same thing as format-out and force-out, but operate on *standard-error* rather than *standard-output*.


  • make-dylan-app is now included in the Windows distribution.


  • String comparison and equality operations are now 10 times faster when they are known to be on byte-strings.


  • The function format-date is now faster.
  • The copy-file method on Unix no longer fails when the path contains spaces.
  • The #"write-date file property has been removed. It was identical to #"modification-date", so use that instead.
  • Iterating over a directory with do-directory will no longer crash on x86_64-darwin.


  • Compiler warnings are now produced when a test or suite is unused. For example, it is easy to forget to add a test to any suite. As a side effect of this change, it is now necessary to organize test suite code in a bottom-up style. That is, you must define tests and suites before including them in a suite definition in your source file. If you don’t, you will receive a warning about an “Illegal forward reference”.
  • Benchmarks are once again supported. See the documentation for details.