Some Windows linking tools, such as MinGW-w64, accept a ".dll" for linking to generate an executable that refers to the ".dll". Other tools, such as Microsoft Visual Studio, need a ".lib" stub library to describe the ".dll" that will be used. The Racket distribution does not include ".lib" stub libraries, but various tools exist to generate one from a ".dll".
To create a "x.lib" using Microsoft Visual Studio tools (to link with "x.dll"):
Create a file "x.def" using the same base name x as in "x.dll".
In "x.def", make the first line EXPORTS, and then write the name of each function that you need to reference from "x.dll" on its own line in "x.def".
Generate "x.lib" with this command:
lib /def:x.def /out:x.lib /machine:mach
Use a suitable platform description in place of mach, such as x64 for 64-bit Windows on x86_64.