Scala 3 Macro Annotations Example

This is a simple example of macro annotations in Scala 3. The approach is described in this blog post.

The sbt project contains two subprojects:

• macros contains the macro annotation definition for the @cached annotation
• examples contains the example usage of the @cached annotation

The example can be run as follows:

sbt examples/run

The expected output is the following:

CACHE MISS for key (1,2)
2
CACHE HIT for key (1,2): 2
2
CACHE MISS for key (2,1)
2
CACHE MISS for key (3,x)
3x
CACHE HIT for key (3,x): 3x
3x

The cache logs a CACHE MISS when an input to the cached method is used for the first time. If the input has been used before, the cache logs a CACHE HIT and returns the cached result.