[hyperrail]

Aside: Why do we use the terms "mutable" and "immutable" to describe those concepts? I feel they are needlessly hard to say and too easily confused when reading and writing.

I say "read-write" or "writable" and "writability" for "mutable" and "mutability", and "read-only" and "read-only-ness" for "immutable" and "immutability". Typically, I make exceptions only when the language has multiple similar immutability-like concepts for which the precise terms are the only real option to avoid confusion.

[forty]

Read only does not carry (to me) the fact that something cannot change, just that I cannot make it change. For example you could make a read only facade to a mutable object, that would not make it immutable.

[iLemming]

> Why do we use the terms "mutable" and "immutable" to describe those concepts?

Mutable is from Latin 'mutabilis' - (changeable), which derives from 'mutare' (to change)

You can't call them read-only/writable/etc. without confusing them with access permissions. 'Read-only' typically means something read-only to local scope, but the underlying object might still be mutable and changed elsewhere - like a const pointer in C++ or a read-only db view that prevents you from writing, but the underlying data can still be changed by others. In contrast, an immutable string (in java, c#) cannot be changed by anyone, ever.

Computer science is a branch of mathematics, you can't just use whatever words you think more comfortable to you - names have implications, they are a form of theorem-stating. It's like not letting kids call multiplication a "stick-piling". We don't do that for reasons.

[Waterluvian]

Same reason doors say PUSH and PULL instead of PUSH and YANK. We enjoy watching people faceplant into doors... er... it's not a sufficiently real problem to compel people to start doing something differently.

[afandian]

"read-only-ness" is much more of a mouthful than "immutable"!

Generally immutability is also a programming style that comes with language constructs and efficient data structures.

Whereas 'read-only' (to me) is just a way of describing a variable or object.