[braythwayt]

I have no idea why they did it, but I have argued for quite some time that const has very little practical value, because its effect is always lexical and local.

To demonstrate that this is so, I suggest that we can write a processor that converts all lets to consts where possible. I also demonstrate that this is so by asking, "What bug will const catch that our tests will not catch?"

_Immutable Data_, on the other hand, is marvellous. Immutability has nonlocal effects, and it is not something that can be trivially verified.

[mpfundstein]

I agree with your assessment, but for me it is a message from the programmer to the reader. Hey this value will not be re-assigned during the following scope block. If I see a let, I know I must be careful. Of course this doesn't apply to properties of objects ... which is a pity!