Don't understand the nickel repl example in the readme

[bew]

Looking at the repl example:

$ ./nickel repl
nickel> let x = 2 in x + x
nickel> x
4

👉 Why isn't this instead?

$ ./nickel repl
nickel> let x = 2 in x + x
4
nickel> x
2                            # or an error? why would `x` be in scope here? for me `x` was only defined for the `x + x` expression

[yannham]

Thanks for reporting!

You're correct. Running let x = 2 in x + x prints 4, and does NOT put x in scope. However, if you use a top-level let without an in, you can add stuff to the environment:

nickel> let x = 2 in x + x
4

nickel>x
error: Unbound identifier
  ┌─ repl-input-1:1:1
  │
1 │ x
  │ ^ this identifier is unbound

nickel> let x = 2 + 2
nickel> x
4

We'll fix the example.

[bew]

Interesting, thanks!