Local bindings are immutable.

Your example demonstrates lexical shadowing of bindings.

This is an equivalent program semantically.

(let [x   1
      x_1 (inc x)
      x_2 (inc x_1)
      x_3 (inc x_2)]
  x_3)

By the rules of lexical scoping, you cannot access the first `x` but it is
never mutated.

Thanks,
Ambrose

On Wed, Feb 11, 2015 at 8:42 PM, gvim <gvi...@gmail.com> wrote:

> Why is this possible in a language based on immutability:
>
> (let [x 1
>         x (inc x)
>         x (inc x)
>         x (inc x)]
>    x)
>
> ;;=> 4
>
> Maybe under the hood (ie. memory registers/pointers etc.) this isn't
> strictly mutation but as a relative newcomer to Clojure I find it goes
> against the grain of what I find elsewhere in the language.
>
> gvim
>
>
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