asdf:component-children
(asdf:component-children parent)
Reader: a parent component's children in load order. A system's children are
its component files, one asdf:cl-source-file per file — a :module
contributes its path prefix to the file names rather than a nested instance —
and a package-inferred sub-system has exactly one child, real ASDF's shape.
Each child's asdf:component-pathname is the
resolved source path and its
asdf:component-parent is the system.
Backend support
Works on all four backends.