load

(load filename)

Reads a file and evaluates every top-level form in it in the global environment, then returns t. Definitions such as defun and setq in the loaded file remain available to subsequent code. A relative filename resolves against the directory of the file doing the load (the entry file for a top-level load), so a program can be run from any working directory and still find a (load "sibling.lisp"). In compiled output the loaded definitions live in the runtime eval interpreter's global environment, so they are reached through eval (e.g. (load "lib.lisp") then (eval '(square 5))). Works in all three backends; the WASM load reads the file with WASI path_open, so the module must be run with a directory granted (e.g. wasmtime run -W gc --dir . prog.wasm).

(load "lib.lisp")
(eval '(square 5))

After loading a file that defines square, the definition is invoked through eval. The WASM backend needs --dir because it resolves the path against the first preopened directory.

load is deliberately not idempotent: loading the same file twice evaluates it twice, matching Common Lisp. For load-once module semantics, see require / provide.