read-from-string

(read-from-string string)

Parses and returns one datum from the given string. It reuses the same reader as read, so on the compiled backends it accepts the same frontend-parity syntax (#S(...), #(...), #\a, ratios, radix integers, ... -- with #., #+/#- and reader labels signaling; the WASM reader's numbers carry integers of any magnitude but no float exponents), and (read-from-string (prin1-to-string x)) round-trips. The interpreter evaluates a #. datum in place (binding *read-eval* to nil makes it signal, per the standard). The optional eof-error-p/eof-value and the :start/:end keyword arguments are not supported -- only the single string argument is accepted. Works in all three backends and is usable as a first-class value (#'read-from-string).

The result is the parsed list (+ 1 2) as data, not its evaluation; pass it to eval if you want the value 3.

Symbols are read with the reader's upcasing, identically on every backend: your symbols and the standard names alike read upcased (there is no fold to a lowercase spelling).