Transformation of Applicative Specifications into Imperative ...

}
9.7. DISADVANTAGES IN USING THE RSL2JAVA TOOL
r e s u l t . append ( " end" ) ;
public void visitPLUS (PLUS r s l _ p l u s ) {
r e s u l t . append ( "+" ) ;
}
public void visitMINUS (MINUS rsl_minus ) {
r e s u l t . append ( "−" ) ;
}
9.7 Disadvantages In Using the RSL2Java Tool
As mentioned in this chapter there have been some advantages involved by
choosing to use the RSL2Java tool in the implementation of the transformer.
However, it turned out during the development process that there were also
some disadvantages. In this section some of the disadvantages will be discussed.
The RSL2Java tool can only translate a subset RSL1 of RSL into Java.
This made the specification written in RSL1 very long and messy. Especially
the lack of let expressions, maps, some operators and the fact that functions
are only allowed to have one return value complicated the matter. Furthermore,
some errors connected to the type decoration of the RSL2Java tool
required the introduction of extra functions.
These problems led to the idea, that a specification of the transformation
should be written in both RSL and RSL1. This was necessary in order to
offer a readable specification for the reader and at the same time to be able
to use the RSL2Java tool. This choice led to a lot of effort in keeping the two
specifications up to date, both during the implementation phase and during
the process of correcting errors. The method for obtaining this was first to
correct the RSL specification and then transfer the corrections to the RSL1
specification. The approach may have complicated the RSL1 specification
more than necessary but were necessary in order to keep both of the two
specifications up to date.
The resulting transformer works as expected, but in some cases the transformation
process is rather slow, especially in cases of specifications containing
nested product expressions. To give an example, it takes a few seconds
to transform a specification without nested product expressions, whereas it
can take up to several minutes to transform a specification of the same size
containing one nested product expression. This is due to the fact that no
code optimization is done in the RSL2Java tool and at the same time it is
very difficult to optimize the code by optimizing the specification in RSL1.
Due to these difficulties no effort is put into optimizing the transformer.
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