# [Pip], 12 bytes

A comment-based solution:

    aQRVa  aVRQa

Takes input as command-line argument; outputs `1` for palindrome, `0` for non-palindrome. [Try it online!]

Uppercase sequences scan as pairs of letters, with the odd letter out being the first one. So the code that gets executed is `a Q RV a`, where `a` is the command-line argument, `Q` is string equality, and `RV` is reverse. Everything after a double space is a comment.

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The best non-comment solution I've found so far is quite interesting, but unfortunately it's 13 bytes ([try it online]):

    x:aQRVaVRQa:x

`aQRVa` works as above: 1 if palindrome, 0 if non-palindrome. Next, the sequence `VRQ` is interpreted as `V RQ`, which evaluates the previous result as a function with argument list `RQ`. This is bizarre, for a few reasons:

- `RQ` is an undefined variable, so it's nil, not a list.
- Evaluating `1` or `0` as a function should be equivalent to calling the functions `{1}` or `{0}`, which return a constant value regardless of the arguments.
- However, there's a bug in the current interpreter such that evaluating `0` actually gives nil. (`1` gives `1`, as expected.)

Thus, `x:aQRVaVRQ` computes either `1` or nil and assigns it to `x`. Then `a:x` assigns that value back to `a`; but since this is the last expression in the program, it is also printed implicitly. (Printing nil results in no output.)

After my next interpreter update, you should get `0` for non-palindromes.

[Pip]: https://github.com/dloscutoff/pip
[Try it online!]: https://tio.run/nexus/pip#@58YGBSWqKCQGBYUmPj////E3MS8xIIcIJEMxDkFQCI3EQA "Pip – TIO Nexus"
[try it online]: https://tio.run/nexus/pip#@19hlRgYFJYYFhSYaFXx////3MSUxNxMMAkA