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Tim Bradshaw



TFEB.ORG Lisp tools

This repo contains a system which will be a collection of fairly miscellaneous Common Lisp tools, which I have written over the years in order to generally get stuff done. Here, a tool is a thing which helps with building programs, loading modules and similar things, rather than something you might use in a program which would be a hack.

  • require-module provides variants of require which will search for modules, as well as the mechanisms to control the search, and also a variant of provide which keeps records of the file which provided a module;
  • install-providers makes use of the records of module providers kept by require-module in order to copy them to places they will be found.
  • build-modules provides a way of compiling a collection of single-file modules, using require-module to locate their sources.
  • feature-expressions provides some tools for reasoning about implementation features after read time.
  • deprecations provides tools for marking functions, generic functions and macros as deprecated, causing an optional compile-time warning and allowing reporting and mapping over deprecated things.
  • asdf-module-sysdcls can help writing ASDF system declarations for single-file modules: it wrote all but the main system declaration for this system.

I hope to add more tools as I disentangle them from the things they're currently entangled with and modernise them where needed. All of the tools are intended to be portable CL except where documented.

The descriptions here are at best partial[^1].



These tools purport to be portable Common Lisp. If they're not that's either a bug in the tools or a bug in the CL implementation. In the former case I very definitely want to know, and I am also willing to add workarounds for the latter although I may be unable to test them on implementations I don't use.

Zero history

All of these tools have long and varied histories. However these histories are entangled with a lot of other code which is not public, so that history is not represented in the publication repo where you are probably reading this.


I planned to use semantic versioning, where the major version number only changes on incompatible changes. However the result of this would be that a complete new tool being added or a huge extension to an existing one would only be a minor version, which seems wrong. So what I'm doing is to modify this: a major version means either an incompatible change, a complete new tool, or a very major extension of an existing tool.

Naming conventions

All of these tools make use of, and often work best with, domain-structured names: packages, modules, features and so on have names which start with a DNS domain name in reverse order and then may continue to divide further. In this case the prefix is org.tfeb is the DNS component and tools is the division within the DNS part.

This naming convention ensures uniqueness of things like package names. It does make typing package-qualified names somewhat irritating: the solution is not to do that but to construct packages which import or use the symbols you need. CL's default package system is very well up to solving this problem, rumours to the contrary notwithstanding: conduit packages can make it a little simpler to express what you want to do, and UIOP's define-package can also do something similar, I think.

Nothing actually cares that names correspond to real DNS domains: some things do care that the namespace is hierarchically structured and big-endian.

Requiring modules with searching: require-module

Although CL now has competent tools for defining and distributing 'systems' of code, in the form of ASDF and particularly Quicklisp, not all bits of code are large enough to justify their use. In particular it's in the nature of the incremental and exploratory programming style encouraged by CL that people[^2] tend to write a bunch of little tools and utilities, living in single source files, which help them get their work done and which they reuse over time. Some of these may be portable, some not, and many of them can be quite small: a tool I use very often is under 50 lines excluding noise, but including docstrings and comments, and I have had smaller ones.

Turning these small tools into ASDF systems[^3] either means combining them into some larger conglomeration of code such as this one, or doubling the number of files you have to deal with because of the system definition files for each small tool. Combining them into a larger conglomeration of code means everything takes longer and costs more; doubling the number of files means the same. Also, of course, the ancestor of require-module predates the common availability of portable system definition tools by many years.

Well, CL has require, provide and *modules* and although these are deprecated, they're not going away any time soon, or in fact ever. So a reasonable approach is to make all the small tools into modules by adding suitable provide incantations, and then to use require to load them. This still leaves the problem that require needs to know where to find the module being required is in the filesystem, and I didn't want to fill code with explicit pathnames, even though logical pathnames make things at least a little better.

require-module provides a souped-up variant of require which has a portable mechanism for searching for and locating files corresponding to modules. In particular it understands how to combine domain-structured module names (org.tfeb.hax.collecting say) with a search list of pathnames to locate a file corresponding to the name which, when loaded, should provide the module. There are mechanisms to define what directories should be searched and in which order, and to wrap code around the process of requiring a module in the manner of CLOS around methods. Finally it also provides a wrapper for provide which keeps a record of the file which provided a given module, which can be used by install-providers (below) to install modules where it expects them to be.

require-module can also take advantage of the fact that require never actually checks that the file or files it loads provides the module being required. So require-module will happily load any file it can find, and doesn't care whether the module is provided or not.

require-module also keeps a cache of the truenames and write dates of the files it has loaded: unless you ask to bypass the cache, files will only ever be loaded once until they are modified, no matter how many times they are required.

Finally, require-module also keeps a structure which maps between modules it has loaded and all the descendant modules of them – modules which were loaded in the process of loading some other module – together with a note as to the file they came from. Using this structure you can ask it to reload a module if it has changed together with any descendant modules which have changed. This is currently experimental.

Logical pathnames

require-module doesn't need you to use logical pathnames, but it does work well with them and I have usually used it that way until recently. Using logical pathnames gives you two advantages:

  • the mechanism for maintaining the search list lets you add & replace a bunch of paths for the same host, and if that's a logical host you can invent new ones, so maintenance becomes easier;
  • there is another level of translation between the names of modules and the physical pathname they come from – for instance by changing the translations of a logical host you can switch between variants of things easily.

In summary you don't have to use logical pathnames, but it can make things easier.


Module names are case sensitive: requireuses string= to compare them. Depending on how you write module names this can make life a little complicated[^4]. This is made more interesting because logical pathnames are really all upper-case. require-module tries to be smart about this:

  • if it is checking a logical pathname as a potential location it uppercases module names;
  • if it is checking a physical pathname then it first tries the name as it is, then downcased, then upcased, where those variants differ.

This typically works reasonably well: if you use module names which are symbols, are searching a physical pathname, are using a case-sensitive filesystem and prefer lowercase filenames, then it will find a lowercase filename on the second try.

The search algorithm

The search process starts by splitting up a domain-structured module name into a list of strings (the set of characters which separate components can be controlled: see below), which it will then variously use as directory and name components for the search:

  • "org.tfeb.hax" is turned into ("org" "tfeb" "hax");
  • :org.tfeb.hax is turned into ("ORG" "TFEB" "HAX") assuming standard reader settings.

These lists, and parts of them, are then used as parts of pathname specifications after possible case fiddling.

There is a list of path specifications to search: see below for how the list is maintained and exactly what can be in it. A path specification should generally specify a wild or partly-wild lisp source file name. Each path specification is searched in turn, and finally a desperation search is done on all of them using only the last part of the module name. The search continues until either a hit is found or there's nothing left to search.

Example: searching for in "CLEY:LIB;MODULES;*.LISP". This is a logical path specification, so only upper-case variants will be tried. Both the compiled file (via compile-file-pathname) and the source file for the following pathnames will be tried[^5]: if both exist then the compiled file will be taken if it is newer, otherwise the source file (with a warning):

  3. (all the other path specifications are searched the same way);
  5. "CLEY:LIB;MODULES;REQUIRE-MODULE.LISP" (desperation search, part 2).

Example: searching for "org.tfeb.HAX" in "/local/lisp/*-loader.lisp". This is a physical path specification so things are more complicated:

  1. "/local/lisp/org/tfeb/hax/HAX-loader.lisp"(case as is);
  2. "/local/lisp/org/tfeb/HAX-loader.lisp" (case as is);
  3. "/local/lisp/org/tfeb/hax/hax-loader.lisp" (downcase 1);
  4. "/local/lisp/org/tfeb/hax-loader.lisp" (downcase 2);
  5. "/local/lisp/ORG/TFEB/HAX/HAX-loader.lisp" (upcase 1);
  6. "/local/lisp/ORG/TFEB/HAX-loader.lisp" (upcase 2);
  7. (all the other path specifications);
  8. (equivalent desperation searches, trying downcase and upcase variants as before, a total of 6 more searches).

In fact the search algorithm is cleverer than this in several ways:

  • if downcasing or upcasing a module name results in no change from something already probed, it is not probed again;
  • for module name has only one component ("foo" say) then the desperation search using the last part of the name only is omitted as a whole, as it would all duplicate the previous search;
  • finally, a table of pathnames probed in the current search is kept, and if a probe would be a duplicate – for instance because the search list has duplicate entries – it is simply omitted, with a possible debugging note.

None of these tricks should alter which file is found for a module: they are all intended just to eliminate duplicate probes of the filesystem.

Package, module, feature

Everything below is exported from will also be present in both *modules* and *features* once this module is loaded – the latter helps a lot with conditionals in init files.

Requiring and locating modules

require-module will search for and require modules. It has one mandatory argument which is the module name, and a fairly large number of keyword arguments. Values for most of the keyword arguments are dynamically passed down[^6], so that recursive calls to require-module will get the same values as the parent call: exceptions are noted below. The keywords and their default values are as follows.

  • verbose will cause it to tell you what it's doing (on *standard-output*), default nil.
  • trace will provide much less output than verbose, on *trace-output*, default nil.
  • debug will turn on some debugging output to *debug-io*, and in particular will cause locate-module to talk about evaded duplicate searches due to the search list. Default nil.
  • quiet will cause some warnings not to happen (quiet and verbose can both be true). Default nil.
  • test specifies the comparison function to use for module names, by default #'string= which is the right default.
  • pretend will cause it not to actually require the module, default nil.
  • force will cause it to forcibly require the module (by removing it from *modules*as the first step), default nil.
  • once will cause it to check the cache of loaded truenames and only load a file if it either has not been loaded previously or if its write date is newer than the cached date, default t.
  • cache will update the cache of loaded truenames when a file is loaded, default t.
  • reload will cause it to reload any dependent modules if possible. Default is nil & this is not inherited from the ambient value. Note that all dependent modules will be reloaded: not just direct children.
  • compile will cause it to attempt to compile the module if it gets a source file name, default nil.
  • use will cause it to use a package with the same name as the module after it is loaded if it exists, default nil. This is not inherited from the ambient value.
  • fallback , if given, should be a final fallback function which will be be used to require a module if no location for it can be found. It is called with one argument, the name of the module. This function is called after the functions on *module-fallback-loaders* are called, and only if none of them loaded the module. Its default value is nil. If this function is called it is assumed to have loaded the module regardless of its return value. Thus no error will be signalled if it is given.
  • error means that failure to require a module is an error, default t.
  • module-path-descriptions is the list of module path-descriptions, default *module-path-descriptions*.
  • hints is a list of pathname designators which are hints as to where the module lives: if given, these are searched first. Default is (), & this is not inherited from the ambient value. This is used by reloading, but can also be used explicitly.
  • module-component-separators is a list of characters which separate module components. The default is the value of *module-component-separators* (which, by default, is (#\.)).
  • module-component-rewriter, if non-nil, is a designator for the function used to rewrite components (see below). The default is the value of *module-component-rewriter*.
  • wrapper-arguments is a list of keyword arguments passed to wrappers, default '().

Wrappers are not yet documented. Reloading is experimental.

require-module returns:

  • its first argument and t if the module was loaded;
  • its first argument and nil if the module was already loaded (no search is done in this case);
  • the first value returned by a fallback loader and tif one of them loaded it;
  • the first value returned by the fallback function and t if it is given and no location was found (note that no error happens here: it's up to the fallback to decide if there should be an error).
  • nil and nil if there is no fallback loaders, no fallback, error is nil and the module was not found;
  • an undefined value or values if pretend is given.

require-module relies on require to do the actual work of loading the file and most of the work of maintaining *modules*. It will only search (and thus only call require on the results of the search) if the module is not already present on *modules*, either because it was not there before the call or because it's just removed it due to the force option.

It is not an error if a module doesn't define a package with its own name when the use option is given, but there will be a warning unless quiet is also given.

*module-fallback-loaders* is a list of function designators which require-module will use as fallbacks by default. Each entry should be designator for a function of one positional argument and should accept all the keyword arguments explicitly passed to require-module. If the function returns true then the module is assumed to be loaded, and its return value will be the first value of require-module. These functions are called before the function given as the fallback argument, if any, and it will only be called if none of them loads the module.

The initial value of *module-fallback-loaders* is ().

locate-module locates a module: it's what require-module uses to find things. It has one mandatory argument which is the module name, and two keyword arguments.

  • module-path-descriptionsis the list of module path-descriptions, default *module-path-descriptions*.
  • hints is a list of possible pathname designators for the module; if given it is searched first. the default is (). This is used by module reloading but can be used explicitly.
  • module-component-separators is a list of characters which separate module components. The default is the value of *module-component-separators* (which, by default, is (#\.)).
  • module-component-rewriter is the module component rewriter, the default being the value of *module-component-rewriter*.
  • verbose makes it say what it's doing, default nil.
  • debug enables some debugging output.

locate-module will return 5 values:

  1. the selected pathname, or nil;
  2. the source pathname, or nil;
  3. the write date of the source pathname, or nil if none was found;
  4. the compiled pathname, or nil;
  5. the write date of the compiled file, or nil if none was found.

If the selected pathname is nil then all the other values will be nil. Otherwise it will be the newest of the source and compiled files, or the only one of them found if both do not exist. In particular it will be eq to exactly one of the other pathnames in this case. All pathnames returned will be truenames.

The reason for this behaviour is that the file located is often a tiny 'loader' shim which never gets compiled[^7], so in this case there's nothing wrong if there is no compiled file. If there is a compiled file but it is out of date it's best to return the source file: it's current, and anything that calls locate-module can choose to compile the file before loading, which is something require-module can do.

locate-module does not either use or update any caches.

require-modules is a shim around require-module which expects a list of module descriptions instead of a module name. It takes all the same keyword arguments as require-module. A module description is either

  • a module name;
  • or a cons of a module description and some arguments to require-modules.

In the second case either require-module (if the nested description is not itself a cons) or require-modules is called with the two sets of arguments appended to each other, with those from the module specification first. Because CL uses the first of any repeated keyword arguments, this means that individual module specifications can override the keyword arguments provided to the function as a whole. require-modules returns a list of lists of the two values returned by each require-module it calls.

requires is a NOSPREAD version of require-modules with a fallback to require. So requires lets you say that you want one or more modules, and if require-module doesn't know how to get them then the system should try require in case it does.

needs lets you express a dependency on modules at compile time: it expands into an eval-when which:

  • at compile toplevel will bind *module-path-descriptions* to have a first element based on the current *compile-file-truename* if that is not nil and then requires a quoted version of its argument;
  • at other timeswill bind *module-path-descriptions* to have a first element based on the current *load-truename* if that is not nil and then requires a quoted version of its argument;

The result of all this is that a file which contains, for instance (needs "foo") will look for "foo" in the same directory as the file, first.

needs has undergone two incompatible changes over its lifetime.

  • Originally it didn't quote its arguments, so this is an incompatible change. If you use strings or keywords as module names this doesn't matter, but it makes things like (needs (:org.tfeb.hax.collecting :use t)) more natural[^8].
  • The rebinding of *module-path-descriptions* is new: see below for why this is done. What this means is that if you load anything using needs which expects to assign to *module-path-descriptions* this will not work.

The recursive behaviour of require-modules is inherited by both requires and needs, and lets you say things like this:

(needs ((:org.tfeb.hax.collecting :org.tfeb.hax.iterate)
        :compile t :use t))

which is sometimes convenient.

clear-module-caches is a function of no arguments which will clear both the cache of loaded files & their write dates and the structure (not really a cache) which maintains the notion of the descendants of a module.

The search list

The list of path descriptions is *module-path-descriptions*. Each entry in this list is a path description, which is one of:

  • a list, which should consist of suitable arguments to make-pathname;
  • a designator for a function of no arguments – the function is called and it should return something suitable to be an element of the searchlist (this process is iterated: if the function returns a function then that will be called in turn);
  • nil which is ignored (this is useful so a function can return nil as a way of declining to provide a useful value;
  • something else, which should be a pathname designator (probably either a list of a string) which is handed to pathname to turn into a pathname.

The initial value of *module-path-descriptions* is a list of one element: a function which, if either *compile-file-truename* or *load-file-truename* is non-nil, will construct a pathname for the module name using it as the defaults.

It is perfectly possible to maintain *module-path-descriptions* manually, and that's how it worked for a long time. There is now a macro which makes this a little easier, perhaps, and a utility which helps with entries which are functions.

define-module-path-descriptions defines module path descriptions. It does this for a particular host (this is one of the reasons logical pathnames are useful), and there are a bunch of options: the most simple ones control whether to add the descriptions before or after the existing ones, and whether to replace existing descriptions for the same host. Rather than describe it in detail here are a couple of examples (yes, this is copping out);

(define-module-path-descriptions ("QL" :after t)

This will add a bunch of pathname descriptions for a logical host named "QL and it will add them after any existing ones. It will replace any descriptions for the "QL" logical host.

(define-module-path-descriptions "-"
  (lambda ()
    (merge-pathnames "*-loader.lisp" (pathname (sb-posix:getcwd))))
  (lambda ()
    (merge-pathnames "loader.lisp" (pathname (sb-posix:getcwd))))
  (lambda ()
    (make-pathname "*.lisp" (pathname (sb-posix:getcwd)))))

This is what my SBCL init file looked like before module-path-descriptions-for-function exists, where it was the first thing that adds to *module-path-descriptions*. The "-" host doesn't exist: it's just there because the macro needs something to be there. Each form in the body is a function which will return a pathname based on the current directory, which means that subdirectories of the current directory get searched first.

There is a weirdness here which is worth noting: define-module-path-descriptions doesn't normally evaluate the forms in its body. But it does arrange for them to be evaluated if they are lists whose first element is lambda, which is why the above works. This is a horrible hack.

define-module-path-descriptions uses an (exported) function called add-module-path-descriptions to do most of its work. You'll need to look at the source to what it does.

module-path-descriptions-for-function is a function which takes two arguments and returns a list of functions suitable for entries in *module-path-descriptions*. Its arguments are:

  • a designator for a function of no arguments which should return either a pathname or nil;
  • a list of pathname specs, which are either pathname designators or partial lists of arguments to make-pathname.

For each pathname spec this will return a a functiony path description which calls the function, and if does not return nil then merges either the result of a suitable make-pathname call (for a listy pathname spec) or a call to pathname (for any other pathname spec) with its result. If the function returns NIL just return NIL.

You can't (easily) use this function with define-module-path-descriptions: you need to use it as above. Note that the function will get called for each pathname spec.

It is tempting to use this function is to provide searching depending on the current file being loaded or compiled:

(setf *module-path-descriptions*
      (append *module-path-descriptions*
               (lambda ()
                 (or *compile-file-truename* *load-truename*))

But this probably will not do what you want and will certainly lead to some nasty surprises. The reason for this is easy to see: consider a file a which, at compile time, does a require-module on some other file, which in turn does a require-module. This will lead to both *compile-file-truename* and *load-truename* to be bound, but to the names of different files. It's then easy to see that there is no order of these two variables in the or expression which can be right in general. This problem can't be solved by *module-path-descriptions*, but it can be solved by needsexpanding to something involving eval-when, which is why needs does that.

Providing modules

As an interface to install-providers, below, there is a function called provide-module: it does exactly what provide does (it relies on provide to do the work) but also maintains an alist, *module-providers* which maps from module names to the files that provided them (from *load-truename*).

Additionally, provides is a counterpart to requires and needs: it lets you state what module or modules a given file provides. Unlike needs it's not a macro because modules should not be provided until they are loaded.

Running code after a module is provided

after-require-module is a macro which can be used in a module, to arrange for the forms in its body to be run after the module has been provided. The forms are wrapped in a block also called after-require-module. This can be used any number of times, and if the module is being loaded some other way it will simply do nothing. For example:

(defun interface (...)


  (register-interface #'interface))

This is particularly useful for modules consisting of several files (with a 'loader' file to load them all): the forms given in after-require-module are run after the whole module is loaded.


require-module-error is a condition class, and all errors signalled directly by any of the functions in the packages are of this class or, potentially, subclasses of it. Currently it's a subclass of simple-error but it may not always be so. Errors signalled by things require-module may call, such as require may not be of this class however.

Other functionality

There is a mechanism for adding wrappers around the process of actually providing a module (after its file has been located). This is not yet documented here, but its main use has been to arrange to forget about system definitions for modules which involve some system definition tool, so the LispWorks development environment doesn't get cluttered up with system definitions that are not interesting. It's also used to implement after-require-module, above. This mechanism is subject to change.

*module-component-separators* is the default list of characters which can separate module names. Its initial value is (#\.), meaning that names are separated by . characters. You could, for instance, set it to be (#\. #\/) which would allow module named like "org.tfeb.ts/test" to parse as ("org" "tfeb" "ts" "test").

*module-component-rewriter* is a variable which may either be nil (the default) or a function designator, and which provides the default module component rewriter. If it is a function designator that function is called on each component of a dotted module name (for "ORG.TFEB.FOSH" the components are "ORG", "TFEB" & "FOSH") and the value it returns is used as the name of the component. This is useful for components which have names which are not valid pathname components: for instance it can be used to rewrite a name like "series/conduit" into "series-conduit"(and this was its original purpose).



(defvar *my-mpds* '())

(define-module-path-descriptions ("TFB"
                                  :module-path-descriptions *my-mpds*)


> *my-mpds*

> (locate-module :org.tfeb.pretend
                 :module-path-descriptions *my-mpds*
                 :verbose t)
> (locate-module :org.tfeb.pretend
                            :module-path-descriptions *my-mpds*
                            :verbose t)
Looking for module :org.tfeb.pretend
 as     /Users/tfb/lib/lw/modules/org/tfeb/pretend/pretend.lisp
 as     /Users/tfb/lib/lw/modules/org/tfeb/pretend.lisp
 as     /Users/tfb/lib/lw/modules/org/tfeb/pretend/pretend-loader.lisp
 as     /Users/tfb/lib/lw/modules/org/tfeb/pretend-loader.lisp
 as     /Users/tfb/lib/lw/modules/org/tfeb/pretend/loader.lisp
 as     /Users/tfb/lib/lw/modules/pretend/pretend.lisp
 as     /Users/tfb/lib/lw/modules/pretend.lisp
 as     /Users/tfb/lib/lw/modules/pretend/pretend-loader.lisp
 as     /Users/tfb/lib/lw/modules/pretend-loader.lisp
 as     /Users/tfb/lib/lw/modules/pretend/loader.lisp

But instead if we had

(defvar *my-mpds* '())

(define-module-path-descriptions ("-"
                                  :module-path-descriptions *my-mpds*
                                  :after t)


> *my-mpds*

> (locate-module :org.tfeb.utilities.permutations
                 :module-path-descriptions *my-mpds*
                 :verbose t)
Looking for module :org.tfeb.utilities.permutations
Probing /Local/packages/lispworks/lib/modules/ORG/TFEB/UTILITIES/PERMUTATIONS/PERMUTATIONS.lisp
Probing /Local/packages/lispworks/lib/modules/ORG/TFEB/UTILITIES/PERMUTATIONS.lisp
Found /System/Volumes/Data/Local/packages/lispworks/lib/modules/ORG/TFEB/UTILITIES/PERMUTATIONS.lisp

This second example is betraying the fact that I'm on a Mac: the mac's filesystem is case-insensitive / case-preserving, so the file is being found with an uppercase filename, when its name is 'really' lowercase. If you provide the debugargument to locate-module you will get even more verbose output.

Falling back to Quicklisp

If you have Quicklisp, this works:

 (:cl-ppcre :fallback ql:quickload))

Which means you can write small programs which rely on Quicklisp to fetch and load things without either an ASDF system definition, or a bunch of explicit eval-whens in the sources to load things at compile time. In fact it is pretty much possible to use needs to informally define systems without a central system definition, even when those systems have dependencies on Quicklisp or other systems.

Another way of doing this, more globally, is

(defun load-module/ql (m &key verbose debug &allow-other-keys)
      (ql:quickload m :verbose debug :silent (not verbose))
    (ql:system-not-found () nil)))

(pushnew 'load-module/ql*module-fallback-loaders*)

I have essentially this code in my init files.


There are no docstrings for anything: there should at least be brief ones. There are no error or warning conditions defined which there should be. Wrappers are not documented. There are too many overlapping reporting options.


require-module does quite a lot of processing of pathnames. It is all intended to be portable but it also turns out to explore some of the boundaries of what implementations support. As an example, SBCL can't currently deal with making partly-wild pathnames, so in SBCL you often need to provide stringy logical pathnames in configurations[^9].

Generally the trace option tells you what you need to know about what is, or is not, being loaded from where without vastly cluttering everything with huge output.

When making module path descriptions based on the current file being compiled or loaded always use truenames and always prefer *compile-file-truename* as otherwise you may get the name of some parent file which has asked to compile the file of interest.

All of the functions accept strings or symbols as module names: they'll complain about anything else rather than blindly calling string.

needs has changed incompatibly so it now quotes its arguments.

locate-module used to return only what is now its first value: this is a compatible change, I think.

A consequence of the caching of truenames is that, so long as the graph of modules and their requirements is a DAG, each file will be loaded just once. That means it's perfectly fine for any file in the DAG just to say (needs ...) to express the files it relies on: if they're already loaded, they won't be loaded again unless they've changed. If the graph has cycles you're in all sorts of trouble, of course.

Installing modules automagically: install-providers

I now use makefiles to install my personal CL modules and systems, and either ASDF or the LispWorks system definition tool to build them once installed[^10]. Previously I used an ancestor of this code. It lives in the package and will add to *modules*.

install-providers will install a set of modules from the files they were originally loaded from into a directory tree under a specified root. It has one argument which is the root under which to install things. The remaining keyword arguments are:

  • providers is an alist of (module-name . providing-file) which tells it what to install, the default being *module-providers* from require-module;
  • really says to really copy the files, the default is nil in which case it will just tell you what it would do;
  • clear will cause it to reset *module-providers* to () after installing, this is true if no explicit list is given and if it is actually installing, and it will refuse to clear the list in any case if an explicit list is given;
  • filter is a function which will be called with the module name and the source & destination paths, and which should return true if the module is to be installed.

The function returns an alist of (source target) of the files copied.


 > *module-providers*
  . #P"/Users/tfb/src/lisp/systems/tools/install-providers.64xfasl")
  . #P"/Local/packages/lispworks/lib/modules/org/tfeb/lw/lw-commands.64xfasl")
  . #P"/Users/tfb/src/lisp/systems/tools/require-module.64xfasl"))

> (install-providers "/tmp/")
 ensure dirs for /tmp/org/tfeb/tools/install-providers.64xfasl
 copy /Users/tfb/src/lisp/systems/tools/install-providers.64xfasl
   to /tmp/org/tfeb/tools/install-providers.64xfasl
 ensure dirs for /tmp/org/tfeb/lw/lw-commands.64xfasl
 copy /Local/packages/lispworks/lib/modules/org/tfeb/lw/lw-commands.64xfasl
   to /tmp/org/tfeb/lw/lw-commands.64xfasl
 ensure dirs for /tmp/org/tfeb/tools/require-module.64xfasl
 copy /Users/tfb/src/lisp/systems/tools/require-module.64xfasl
   to /tmp/org/tfeb/tools/require-module.64xfasl

Building installed modules: build-modules

I have a significant collection of single-file modules which generally don't have overriding ASDF or other system definitions. require-module and its wrappers – needs is the interface I use most commonly – will arrange for modules which exist only as sources or for which the FASLs are out of date to be compiled on demand if needed. Sometimes it's nice to point at a whole collection of module files in a source directory and say 'compile all of the installed versions of these that need to be compiled': that's what build-modules is for.

compile-installed-modules ensures installed copies of a number of single-file modules are compiled, using locate-module to find the installed modules to consider. Arguments:

  • prefixis a string designator for the module prefix, canonicalised to an upper-case string;
  • filesis a list of pathname designators (typically source files, but only the name components of the pathnames are used) corresponding to the modules to be compiled.

Keyword arguments:

omit is a list of pathname designators (or a single pathname designator) of files to omit – generally these will be wild pathnames – default (); only is the opposite of omit – if given it means consider only these files – default (); force, if true, says to compile the modules even if the compiled files seems already to be up to date, default nil; verbose says to be more verbose, default nil; pretend says to pretend, default nil.

compile-installed-modules returns a list of the things it compiled. Each element of the list is a list of the local source file, the corresponding module source file, and the module name.

An example

Pretending to compile the modules in the tools source directory.

> (compile-installed-modules
   "" (directory "*.lisp")
   :omit '("sysdcl" "*-cometh" "*-loader")
   :pretend t :verbose t)
Would skip /System/Volumes/Data/Local/tfb/packages/quicklisp/local-projects/org/tfeb/tools/ensuring-features.lisp
 from /Users/tfb/src/lisp/systems/tools/ensuring-features.lisp
 as fasl is newer
Would skip /System/Volumes/Data/Local/tfb/packages/quicklisp/local-projects/org/tfeb/tools/require-module.lisp
 from /Users/tfb/src/lisp/systems/tools/require-module.lisp
 as fasl is newer
Would compile /System/Volumes/Data/Local/tfb/packages/quicklisp/local-projects/org/tfeb/tools/build-modules.lisp
 from /Users/tfb/src/lisp/systems/tools/build-modules.lisp
Would skip /System/Volumes/Data/Local/tfb/packages/quicklisp/local-projects/org/tfeb/tools/install-providers.lisp
 from /Users/tfb/src/lisp/systems/tools/install-providers.lisp
 as fasl is newer

Here only build-modules itself would need to be compiled, as the FASL is out of date with the source.


build-modules is only really useful for single-file modules which deal with their own interdependencies: it's not anything like a replacement for a system definition tool. I have lots of these however, so it's useful for me.

Package, module

build-modules lives and provides

Implementation features: feature-expressions

CL's #+ and #- syntax lets you evaluate feature expressions – boolean expressions based on the *features* variable – at read time, but without cleverness no later than that. This is ideal to cope with syntax that can't be read unless some feature is present, such as packages which may not exist, or for differences between implementations, as a compiled file whose source was read by one implementation is not likely to be useful in another.

But sometimes you want to check features of the implementation later than read time, or you want to know that a feature expression that was true at read time (and hence probably at compile time) is still true at load time (and hence probably at run time). Sometimes also you might want to evaluate a feature expression directly, or to more generally write conditionals based on feature expressions. This is what feature-expressions lets you do.

evaluate-feature-expression is a function which evaluates feature expressions as described in the spec, with the possible restriction that operators (or, and etc) need to be symbols in the CL package. It has a compiler macro which will compile feature expressions which satisfy constantp into equivalent code.

feature-case is a macro which dispatches on feature expressions. It is like typecase rather than case: its body is a series of clauses of which the first elements are either feature expressions or one of the symbols otherwise or t, and whose remaining elements are forms to be evaluated if the feature expression is true, or in the case of otherwise or t, in any case. An example:

  ((or :SBCL :CMUCL)

One result of these rules is that, if you expect there to be features named otherwise or t (which seems unlikely), you would need to check for them by a feature expression like, for instance (or otherwise).

ensuring-features is a macro designed to be used at top level, and whose purpose is to make assertions about various features at various times in the processing of the file. Its body consists of number of clauses. Each clause consists of (<time> [<feature-expression> ...]), where <time> either a specification suitable for eval-when or t, which is a shorthand for (:compile-toplevel :load-toplevel :execute). Each <feature-expression> is a feature expression, to be evaluated by evaluate-feature-expression as above.

ensuring-features expands into suitable eval-when expressions which will ensure that the specified feature expressions are true at the appropriate times, signalling an informative error if not.



This will ensure that is present as a feature at load time (but it need not be at compile time or any other time). feature-expressions contains this form in its own source code: the feature will not be present when it is being compiled, but will be when it is being loaded.

Package, module, feature

feature-expressions lives in, provides and also pushes a feature with this name onto *features*.

Deprecating code: deprecations

Sometimes you don't get things right the first time, so you want to mark old interfaces as deprecated. deprecations lets you define things as deprecated: something which is deprecated will cause a warning if code that uses it is compiled, unless such warnings are suppressed, and once code which uses deprecated functionality has been compiled it is possible to introspect about what files referred to what deprecated functionality.

You can deprecate functions, generic functions, macros and symbol macros. You can't deprecate variables, because I could not work out a way to do this without changing the semantics of code which refers to them: see below.

All of the defining macros for deprecated functionality are plug-compatible with the standard defining macros: (defun foo ...) becomes (define-deprecated-function foo ...) with no other changes needed.

Deprecations may be signalled as a subclass of style-warning at compile time, and are also recorded. You can inhibit the compile-time warnings and also establish a local dynamic extent for deprecation recording so you can know which deprecations were noticed during which compilation.


define-deprecated-function will define a deprecated function. It is just like defun except that compilation of code which calls the function will, unless inhibited, signal a warning, and will in any case record information about it. If the function has a docstring, this is used as the deprecation notice.

define-deprecated-generic-function does the same thing for generic functions. In this case the deprecation notice is pulled from the :documentation clause, if any. As with functions the deprecation warning happens at the time code calling this function is compiled.

define-deprecated-macro defines a deprecated macro: the deprecation notice comes from the docstring, if any. The deprecation warning will happen when the macro is expanded.

define-deprecated-symbol-macro defines a deprecated symbol macro. These can't have deprecation notices as there is no room in the syntax for such a thing (symbol macros don't have docstrings). The deprecation warning happens when the symbol macro is expanded.

deprecation-warning is a subclass of style-warning used for deprecations. It has readers:

  • deprecation-warning-thing is the name of the deprecated thing;
  • deprecation-warning-what is the sort of thing that was deprecated, which may be :function, :generic-function, :macro, :symbol-macro or possibly some other keyword symbol (but in fact not);
  • deprecation-warning-notice is the deprecation notice, or nil;
  • deprecation-warning-location is the truename of the file where the deprecation was noticed, or nil if there is no file.

*inhibit-deprecation-warnings*, if true, will cause deprecation warnings to be inhibited during compilation. If it is true then deprecations will be recorded but no warnings will happen. Default value is nil.

map-deprecations maps a function over information about deprecated functionality: the function is called with four arguments:

  • the location of the deprecation as above;
  • a list of the names of every deprecated thing in that location, with each name occurring only once;
  • a list of the 'whats' of the deprecated things, one for each thing, which are keywords, as above;
  • a list of the deprecation notices for each thing, as above.

map-deprecations returns no values.

clear-deprecations will clear the recorded deprecations. Returns no values.

report-deprecations produces a report on users of deprecated functionality. It has two keyword arguments:

  • stream is the stream to print on, default *standard-output*;
  • clear will clear the set of deprecations after producing the report, default nil.

It also returns no values.

with-deprecations is a macro which establishes a dynamic context for reporting and warning about deprecations. Syntax is (with-deprecations (&key (inhibit nil)) ...): within the dynamic extent of the macro's body the deprecation reporting functions will report only deprecations which occurred during the extent of the body (and clear-deprecations, map-deprecations etc will see only those deprecations). You can also optionally inhibit declaration warnings during the dynamic extent of the body.


Given a file containing this:

(define-deprecated-generic-function bar (x)
  (:documentation "use fish")
  (:method (x)

(define-deprecated-function foo (x)
  "use new-foo"
  (bar x))

(defun bone (x)
  (foo x))

Then compiling this file without deprecations inhibited will produce two warnings which might appear as follows:

Warning in foo: deprecated generic function bar in /path/to/x.lisp (use fish)
Warning in bone: deprecated function foo in /path/to/x.lisp (use new-foo)

Alternatively you can choose to inhibit warnings and report:

> (with-deprecations (:inhibit t)
    (compile-file "x.lisp")
[... no deprecation warnings ...]
 generic function bar (use fish)
 function foo (use new-foo)

Note that if the order of the definition of bar and foo are inverted you'll only get one warning & recorded deprecation: that's because it's all done by compiler macros.


Deprecations for functions and generic functions are implemented by compiler macros: if you already have compiler macros for deprecated functionality things will not work as you expect. Deprecations for macros and symbol macros are implemented by adding a form to the macro definition, which I think should be safe.

Because things are implemented by compiler macros you won't see most deprecations unless you compile your code.

An earlier version of the code attempted to implement deprecations for global variables by defining the global variable name as a symbol macro which expanded to a secret version of the name, producing a deprecation warning along the way. This doesn't work because, if *foo* is deprecated then (let ((*foo* ...)) ...) binds *foo* lexically, and you can't have symbol macros for symbols declared special. So such a system inevitably breaks the semantics of the program. I don't think there is any way to deal with this problem portably.

Because deprecation warnings are warnings and because the warning class is documented & has documented readers you can handle them, muffle them, and so on. For instance:

> (handler-case
      (compile-file "x.lisp")
    (deprecation-warning (w)
      (error "deprecated: ~A" w)))

This came, with permission, from an idea by a friend of mine in an answer on Stack overflow, but it is now a lot more elaborate than that code was.

Package, module

deprecations lives in and provides

Writing ASDF files for modules: asdf-module-sysdcls

Both this collection of tools and my hax collection are really a lot of mostly-independent modules with occasional dependencies. There's a single ASDF system definition only because I was too lazy to write lots of little ones and I never actually use it to load them other than for testing.

asdf-module-sysdcls lets you easily write a large number of similar ASDF system definitions for single-file modules, so that people who do use ASDF for them can load individual modules. So now both this system and the hax system have system definitions for each module.


write-asdf-module-sysdcl will write a system declaration for a module which is part of a system. It has two required arguments and two keyword arguments. The required arguments are:

  • module/desc is either a string naming a module or a cons of a string naming a module and some keyword arguments to defaystem;
  • of is the name of the system of which module/desc is a component, and is used to construct the full names of things.

The keyword arguments are:

  • preface is a list of defsystem keyword arguments which are simply stuffed into the defsystem form, with the default being ();
  • default-pathname is used to construct the filename of the system definition file that's written, with the default being either *load-pathname* or *default-pathname-defaults*.

This function exists mostly to be in the expansion of the following macro, which is really the interface to this code.

define-asdf-module-sysdcls lets you write ASDF system declarations for many modules in one go. Syntax

(define-asdf-module-sysdcls <of> (<kw> <val> ...) <module/desc> ...)


  • <of> is the system of which the modules are a part;
  • <kw> <val> ... are keywords and values for defaystem;
  • <module/desc> ... are modules or modules with more defsystem options.

No arguments to this macro are evaluated.


It's easiest to describe what happens by example. Given a file a.lisp which contains (suitable package setup forms and)

(define-asdf-module-sysdcls "org.tfeb.a"
    (:description "A subsystem of the TFEB a system"
     :version "1.0.0"
     :author "Tim Bradshaw")
  ("two" :depends-on ("closer-mop"))

Then loading this file will cause two files to be written in the same directory: will contain

;;;; Module of org.tfeb.a

(in-package :asdf-user)

(defsystem ""
  "A subsystem of the TFEB a systrm"
  "Tim Bradshaw"
  ((:file "one")))

org.tfeb.a.two.asd will contain

;;;; Module org.tfeb.a.teo of org.tfeb.a

(in-package :asdf-user)

(defsystem ""
  "A subsystem of the TFEB a systrm"
  "Tim Bradshaw"
  ((:file "one")))

And that's what it does. For more comprehensive (or at least larger-scale) examples look at the files with names like write-*-sysdcls.lisp in this system and also the hax system: those files wrote most of the system definition files for these systems.


A future version of this module may be able to generate both the main defsystem and all the module systems from one form, which would avoid keeping multiple lists of modules.

Package, module

asdf-module-syadcls lives in and provides

The TFEB.ORG tools are copyright 2002, 2012, 2020-2022 Tim Bradshaw. See LICENSE for the license.

[^1]: This README also has footnotes which GitHub does not support. You'll just have to make sense of that.

[^2]: Well, I don't know how other CL programmers work: I do know that I do this though.

[^3]: Or systems in one of the system definition facilities which existed before ASDF, of course.

[^4]: I write them as keyword symbols, so my modules always end up with upper-case names.

[^5]: Note that, here and below, I am writing pathnames as strings. This is just because I am being lazy: the system works in terms of pathnames, not strings.

[^6]: The combination of &rest args &key ... and CL's carefully-thought-out leftmost-first-duplicates-allowed keyword argument handling makes this delightfully simple.

[^7]: And, in fact, such loader shims often can't be compiled as they rely on things changing during the load of their source.

[^8]: It's hard to see a case where having needs not quote its arguments is useful since whatever values it uses would need to be available at compile-time anyway, which means you'd already almost certainly have to use eval-when. In any case, if you want what needs does without the autoquoting, you should now use (eval-when (...) (requires ...)).

[^9]: SBCL's behaviour is reasonable: what should (make-pathname :name "*-loader" ...) do? Unfortunately it also leaves no way of making pathnames which have partly-wild components other than parsing namestrings.

[^10]: A key to making this work with ASDF is to turn off output translations and keep the compiled files alongside their sources.

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    Dependents (0)

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      • Quicklisp