Transformation of Applicative Specifications into Imperative ...

8.3. SPECIFICATION OF THE TRANSFORMER
The TRANS map maps each type of interest to the corresponding variable
name. This map is established from the user input and is used both
during the check for transformability and during the transformation phase
in order to figure out what the type names of the types of interest are and
in order to do proper variable replacements.
The TYPINGS Map
The map TYPINGS is defined as follows:
TYPINGS = Id →m Id ∗
The TYPINGS map maps type name identifiers to the list of type identifiers
obtained by recursively expanding the right hand side of the type definitions.
This means that the type definition:
results in the TYPINGS map:
A = B × C,
B = D,
C = A,
D = Int
TYPINGS =
[ A ↦→ 〈B, C, D, A〉,
B ↦→ 〈D〉,
C ↦→ 〈A, B, C, D〉,
D ↦→ 〈〉 ]
The TYPINGS map is used to check that types of interests are not recursively
defined and that they are not part of sets, lists and maps. The
RSL type checker only checks that types are not recursively defined through
abbreviation type definitions, while recursion through union, short record
and variant type definitions is allowed. For example, a type definition of the
form:
Elem,
Collection == empty | add(Elem, Collection)
is allowed in RSL but not allowed when using the transformer.
The value of the TYPINGS map is computed in the beginning of the
transformation in the function TRClassExpr and this value is not altered
during the transformation.
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