I'm a palindrome. Are you?
Brachylog (2), 3 bytes in Brachylog's codepage

I↔I


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This is a full program that takes input via standard input (using Brachylog's syntax for constants, i.e. strings are enclosed in double quotes), and outputs via standard output. The outputs are true. for a palindromic input, and false. for a non-palindromic input.

Not only is this program palindromic, it also has left/right (and probably in some fonts up/down) mirror symmetry.

Explanation

In Brachylog, capital letters mark points in the program which have identical values; this is used almost like an electrical circuit to carry information from one part of the program to another. One consequence of this is that if you enclose a command between an identical pair of capital letters, you're effectively asserting that the command's input and output are the same. Brachylog implicitly takes input, so in this case we're also asserting that the input to the command is the same as the input to the program. In this program, we're using the command ↔, which reverses things (in this case, strings); so the program effectively asserts that the input is the same forwards and backwards.

A full program (as opposed to a function) in Brachylog returns a boolean, false. if there's no way to make all the assertions in the program correct at once, or true. if the assertions in the program are all compatible with each other. We only have one assertion here – that reversing the input does not change it – so the program acts as a palindrome checker.