spec: similar sounding nomenclature is confusing

[griesemer]

In the spec we use the following phrases:

1) integer value
2) value of integer type
3) value of type int (or int8, int16, etc)
4) representable as a value of type int (or int8, int16, etc)

They are very similar in English but mean different things in the spec:

1) -> a (typed or untyped) constant value that is integer (1, 2.0, -4.0 + 0i)
2) -> a typed value that has one of the signed/unsigned integer types (byte, int,
uint8, etc.)
3) -> a value of a concrete type int, int8, etc.
4) -> a value that can be represented w/o loss of accuracy as a value of a specific
type

We should clean this up, and/or introduce a section explaining the nomenclature. As is,
the English differences are small, but the spec implications are large.

[griesemer]

Comment 1:

https://golang.org/cl/6903048/ is an example where this came up: The section on
array types says:
The length is part of the array's type; it must evaluate to a non-negative constant
representable by a value of type int.
r prefers if this would say:
The length is part of the array's type; it must evaluate to a non-negative constant
representable by an int.
The former phrase (representable by a value of type int) was chosen for now since it's
the common phrasing used elsewhere.

[rsc]

Comment 2:

Labels changed: added go1.3maybe.

[rsc]

Comment 3:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 4:

Labels changed: added repo-main.

[griesemer]

4. has been addressed with an explicit definition of "representability" (https://go-review.googlesource.com/57530)
5. all uses of "value of type T" in the spec are very clear
6. all uses of "value of integer type" in the spec are also clear (no ambiguities)
7. all uses of "integer value" have been clarified over time - it's always a value of integer type or an untyped integer constant (never an untyped constant that is not an integer constant but happens to have an integer value, such as 1.0). Furthermore, the section on numeric types defines each set as a set of "integer or floating-point values" which defines the term.

Closing.