That's not possible, currently. Hoot is a cross-compiler, so what you're trying to do in your snippet is kind of like running an ARM executable on x86 without a virtual machine. Everything in the (hoot ...) namespace is only usable when compiling to wasm. For example, (hoot ffi) is for calling functions on a wasm host, not native Guile. Likewise, Guile's (system foreign) provides a C FFI and couldn't be used with Hoot. The Guile VM is the host environment that runs the compiler, and the browser is the target that runs the compiled wasm. In the future, we'd like to host the Hoot compiler in wasm, so that you could do the interactive development we're all used to doing with Geiser, but that's a ways off. Hope this helps!