crazy idea: change the `type` keyword

[JeffBezanson]

Over time, this keyword has increasingly bothered me. There are several problems:

• type is a very generic word and I'd just as soon leave it available for variable names (and keyword arguments!)
• There are now several kinds of types, so it seems strange to use type to refer only to concrete, mutable, struct-like types.
• type is the most obvious type-defining keyword, but usually immutable is preferable and recommended.

Here are some alternate keyword suggestions:

• mutable -- opposite of immutable!
• struct -- at least says something about what sort of type it is
• reftype -- for "reference type", which also conveys some of its key properties

[johnmyleswhite]

Making the word type usable in other contexts would be great.

[quinnj]

I do like mutable for consistency.

[tknopp]

If this is done, it should be done ASAP so that it can be included in 0.6

[joa-quim]

If this is going to happen, than use what everybody recognizes before thinking: struct

[KristofferC]

I also think type is a bit awkward. When I explain it to other people I usually say "like a struct" so +1 for that.

[andyferris]

If this is going to happen, than use what everybody recognizes before thinking: struct

I thought immutable was like a struct?

+1 for mutable

[tknopp]

immutable has the memory layout of a C struct
type has the mutability of a C struct

Thus struct is related to both. I think mutable instead of struct is better to clarify this.

[joa-quim]

Any variable is mutable. Assigning that label to a universally recognized name (a struct) seams all but clear for me.

[goszlanyi]

For someone coming from Fortran the keyword type is already natural.
For someone coming from C the keyword struct would be natural.
For someone using immutable a lot, the opposite keyword mutable would be natural.

So maybe we should leave it as is.

[tknopp]

struct{mutable}
struct{immutable}

or

record{mutable}
record{immutable}

if a more descriptive form is desired.

[JeffBezanson]

If we use struct then the syntax for immutables can be immutable struct (with the struct part being optional at least initially).

I suspect Fortran programmers are familiar with the term "struct".

[barche]

+1 for mutable because of consistency. If struct were chosen, wouldn't consistency dictate changing immutable to something like const struct? ;)