8.6 Application example

This section contains an example of a complete Dylan application that uses a generic factorial calculation routine to return the value of the factorial of 100. Two libraries are defined: the factorial library provides an implementation of the generic factorial routine, and the factorial-application library provides a method that calls the generic routine and returns the appropriate result.

File: fact.lid. LID file describing the components of the factorial library.

Library:  factorial
Synopsis: Provides a naive implementation of the factorial
          function
Keywords: factorial, integer, simple, recursive
Files:    fact-def
          fact

File: fact-def.dyl. Defines the factorial library and its one module.

Module: dylan-user

define library factorial
  use dylan;
  export factorial;
end;

define module factorial
  export fact;
end;

File: fact.dyl. Defines the method for calculating a factorial.

Module: factorial

define generic fact(n);

define method fact(n == 0)
  1;
end;

define method fact(n)
  n * fact(n - 1);
end;

File: app.lid. LID file describing the components of the factorial-application library.

Library:        factorial-application
Synopsis:       Computes factorial 100
Files:          appdef
                app
Start-Module:   factorial-application
Start-Function: main

File: appdef.dyl. Defines the factorial-application library and its one module.

Module: dylan-user

define library factorial-application
  use dylan;
  use factorial;
end library;

define module factorial-application
  use dylan;
  use factorial;
end module;

File: app.dyl. Defines a routine that calls the factorial routine.

Module: factorial-application

define method main (#rest ignore)
  fact(100);
end method;

The following example demonstrates how files of foreign source code and resource files can be integrated into a Dylan library:

Library:        app-with-foreign-code
Synopsis:       Uses some C code and resources
Files:          dylan-code
C-Source-Files: first.c 
                second.c 
C-Header-Files: headers.h 
RC-Files:       extra-resources.rc

---

Common Dylan and Functional Extensions - 31 Mar 00