std/path

An immutable filesystem path: a nominal newtype over string. Zero-cost: at runtime a Path is its UTF-8 string, with no wrapper box. Nominal at typecheck so a Path never silently mixes with a raw string ; every combinator returns a fresh Path rather than mutating in place.

The two halves of a filename, as returned by basename.

RETAINED against its own redundancy: filename() / name() / extension() cover every use, and this should have gone with them, but removing it makes vader test lib/std/path panic in to_posix, a function it never touched (no field replace_chars_where on Path). Bisected: ADDING the three views is fine, REMOVING this is what breaks, so it is a materialisation bug the removal merely exposes. tests/vader_e2e.test.ts runs that isolated mode per stdlib module, so the panic is CI-visible. See TODO.md; delete this once fixed.

Rewrite OS-native path separators to the canonical /. The compiler keeps / as its single internal separator (module discovery, the module index, and vader/front/resolver::join_path are all /-based) so a path entering from an OS boundary that may carry \ (Windows CLI arguments, env vars) must be funnelled through here first, otherwise parent / filename (which split on SEP) silently return empty. POSIX paths pass through unchanged. Takes and returns a raw string, not a Path: the compiler internals it serves (vader/front/resolver::loader, vader/tools/lsp/protocol::uri) are string-based, and the CLI-side Path conversion stops at their boundary. Nothing technical forces this any more: a Path -> Path signature used to panic in midir on the chained cast inside, which is fixed: it is scope.

Wrap an existing string as a Path. No validation: assumes the caller has produced a syntactically valid path.

The empty path (""). Useful as an identity for join / as a default.

Return the underlying string representation. Inverse of to_path.

True iff the path starts with the separator (/foo). Empty paths are considered NOT absolute.

Parent directory: everything before the last separator. Returns the empty path when there's no separator, or / when the path is at the filesystem root.

Last segment (filename or directory name). For a path with no separator, returns the whole path's string.

Both halves of the final segment at once. Prefer name() / extension().

The final segment without its extension.

One of three views on the last segment, none of them overlapping: filename() gives toto.zip, name() gives toto, extension() gives zip.

The final segment's extension, without the dot.

One of three views on the last segment, none of them overlapping: filename() gives toto.zip, name() gives toto, extension() gives zip. Kept separate rather than returning both halves at once, so a caller wanting one doesn't pay for the other being built.

Append a sub-path. Adds a separator between segments unless one is already present. If other is absolute (starts with /), it REPLACES self (Java Path.resolve semantics).

True when self starts with prefix on a segment boundary, so /foo/bar starts with /foo but /foobar does NOT. Useful for "is this under that directory" checks.

True when self ends with suffix on a segment boundary. Same segment-aware rule as starts_with.

Collapse . and .. segments. Purely lexical: does NOT touch the filesystem (no symlink resolution, no existence check). Preserves an absolute prefix when present.

Path separator codepoint. POSIX-only in MVP (/).

Path separator as a string: useful for direct concatenation.