Transformation of Applicative Specifications into Imperative ...

CHAPTER 8. SPECIFICATIONS
8.4.1 More Than One Return Value
As the RSL2Java tool can only handle functions with one return value, it
is necessary to change functions with more than one return value. This is
achieved by introducing short record definitions consisting of fields representing
all the types returned by the function. An example of such a change
is shown in Example 8.2.
Example 8.2 – From many return values to one return value
RSL specification:
value
CheckOptValueExprPairList :
OptionalValueExprPairList × MapType × TYPINGS ×
FUNC × TRANS × ENV × TYPES →
Bool × ENV × TYPES
CheckOptValueExprPairList(
ovel, et, typings, func, trans, env, types) ≡
case ovel of
ValueExprPairList(vel) →
CheckValueExprPairList(
vel, et, typings, func, trans, env, types),
NoValueExprPairList → (true, env, types)
end
RSL1 specification:
type
BOOL_ENV_TYPES ::
bool : Bool envMap : ENV typesMap : TYPES
value
CheckOptValueExprPairList :
OptionalValueExprPairList × MapType × TYPINGS ×
FUNC × TRANS × ENV × TYPES →
BOOL_ENV_TYPES
CheckOptValueExprPairList(
ovel, et, typings, func, trans, env, types) ≡
case ovel of
ValueExprPairList(vel) →
CheckValueExprPairList(
82