Naming of arrays / sequences

[treiher]

Context and Problem Statement

The current use of the terms array and sequence is inconsistent:

Specification: type T is array of E
Python: Array, ArrayType, ArrayValue
SPARK: Message_Sequence, Scalar_Sequence

The mainly used term array might not be the most suitable.

Considered Options

O1: Consistently use array

Specification: type T is array of E
Python: Array, ArrayType, ArrayValue
SPARK: Message_Array, Scalar_Array

+ Specification syntax is similar to Ada, although not identical
– Specification uses same term as Ada, although semantics differ: no specification of index type, no direct access to array elements possible
– array often refers to collection of fixed-size elements, which is not necessarily the case in our specification

O2: Consistently use sequence

Specification: type T is sequence of E
Python: Sequence, SequenceType, SequenceValue
SPARK: Message_Sequence, Scalar_Sequence

+ Makes divergent syntax and semantics to Ada arrays clear
+ Similar use in ASN.1
– Name conflict with Python´s typing.Sequence

O3: Consistently use list

Specification: type T is list of E
Python: List, ListType, ListValue
SPARK: Message_List, Scalar_List

+ Makes divergent syntax and semantics to Ada arrays clear
– list usually refers to collection of heterogeneous elements, which is not the case here
– Name conflict with Python´s typing.List

O4: Use array and sequence interchangeably

Specification: type T is array of E
Python: Array, ArrayType, ArrayValue
SPARK: Message_Sequence, Scalar_Sequence

+ No changes needed
– Inconsistent

Decision Outcome

O2

[treiher]

O2 seems to me to be the best option.

[senier]

I agree that O2 is the cleanest solution.