1. A method, comprising: providing an input source program to a translator, wherein: the input source program includes one or more expressions involving one or more instances of dynamic collection attributes (DCAs); the DCAs include data elements capable of haying a variable number of indexed members at run time; a specification of the one or more instances of DCAs includes at least: a name, a type, an index, and one or more collective properties; the type specified for the one or more instances of DCAs establishes the type of collection and the type of members in the collection, for the corresponding one or more instances of DCAs; the one or more instances of DCAs have member-type properties determined by types of the indexed members of the DCAs; and the one or more instances of DCAs have specified collective properties that are distinct from the member-type properties; automatically inferring, using a translator, additional collective properties for the one or more instances of DCAs based on the type specified for the corresponding one or more instances of DCAs, which were not included in the specified collective properties, using semantics for relationships of collections; automatically translating the one or more expressions to corresponding computer executable expression representations based at least in part on the specified collective properties and the additional collective properties; and providing the computer executable output program representation as an output.