Decision 1. Odin's #load and #load_directory are the model, spelled as
ordinary named calls — an s-expression language already has a head
position and does not need Odin's `#`. (embed "p") is a [u8], (embed "p"
string) is a string, and (embed-dir "d") is a [n EmbedFile] sorted by
name.
Two spellings rather than one that changes type with its context. Odin
threads a type_hint everywhere and can afford it; with structural
equality and no implicit widening, the same text meaning two types here
would be a wart. The path is a literal and resolves relative to the file
the form is written in, both of which are Odin's rules and for Odin's
reasons: the bytes must be in hand before any value exists, and a
package's assets must not depend on where flan was invoked from.
The bytes reach the program as a [Str] node typed [u8], not as a [Bytes]
prim over a string. [Bytes] is identity — emit.ml lowers String and
Slice _ to the same %slice — and wrapping the literal in a prim would
make the node non-constant, so an (embed-dir) bound with defconst could
not be an LLVM constant. Both string emitters take the bytes and ignore
the node's type, so it is the same constant either way and one a global
can hold. emit.ml's escape is byte-exact, so a PNG survives the .ll.
The directory lookup is a linear scan in the prelude over a slice of
EmbedFile. A directory embed is tens of entries out of cache-warm
.rodata, and a compile-time perfect hash would be a build-time map with
its own failure modes that nothing has asked for. Sorted because readdir
order is filesystem-dependent and an unsorted embed would make two
builds of identical sources emit different .ll.
The slice points into .rodata, so a store through it segfaults at -O0
and is deleted at -O2 — the same measured trap the prelude's ASCII-case
note describes for (bytes "Hi"). Inherited, not widened; clone into a
Vec for a mutable copy.
Joseph Ferano
1d7f5e1c85