checkpoint Package Functions

The checkpoint package stages a published model's tensors into packed float arrays: the half of reading a checkpoint that every file format shares. The safetensors reader is written over it, and so is the GGUF reader. It is written in rontolisp itself and loaded on first use like geom; it reaches for nothing but the byte-stream primitives and rontolisp:widen-float-bits, so it runs on every backend that has a filesystem. It is not part of Common Lisp; reference its names with the checkpoint: qualifier.

Three facts shape it. A stream cannot reposition (file-position answers nil), so a reader walks its file front to back and passes over what it does not want with checkpoint:skip-bytes. A packed (unsigned-byte 16) vector costs eight bytes an element on the interpreter and the JVM, so f16 / bf16 bits are staged in chunks of a million elements through one reused buffer -- stage-float-bits takes the STREAM, never a whole staged tensor. And make-array :element-type answers a boxed array for a type it does not know, so make-tensor is the one allocation path and checks what it got.