feat: add File.glob for file pattern matching (issue 15)

Add File.glob(pattern) effect operation that returns a list of file
paths matching a glob pattern (e.g., "src/**/*.lux"). Implemented
across interpreter (using glob crate), JS backend (handler-based),
and C backend (using POSIX glob.h).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -225,7 +225,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.59.0",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -392,6 +392,12 @@ dependencies = [
  "wasip3",
 ]
 
+[[package]]
+name = "glob"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
+
 [[package]]
 name = "h2"
 version = "0.3.27"
@@ -772,6 +778,7 @@ dependencies = [
 name = "lux"
 version = "0.1.6"
 dependencies = [
+ "glob",
  "lsp-server",
  "lsp-types",
  "postgres",
@@ -1182,7 +1189,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.59.0",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -1475,7 +1482,7 @@ dependencies = [
  "getrandom 0.4.1",
  "once_cell",
  "rustix",
- "windows-sys 0.59.0",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]

Cargo.toml

@@ -17,6 +17,7 @@ reqwest = { version = "0.11", default-features = false, features = ["blocking",
 tiny_http = "0.12"
 rusqlite = { version = "0.31", features = ["bundled"] }
 postgres = "0.19"
+glob = "0.3"
 
 
 [dev-dependencies]

src/codegen/c_backend.rs

@@ -1166,6 +1166,7 @@ impl CBackend {
         self.writeln("    void (*mkdir)(void* env, LuxString path);");
         self.writeln("    void (*copy)(void* env, LuxString src, LuxString dst);");
         self.writeln("    LuxList* (*readDir)(void* env, LuxString path);");
+        self.writeln("    LuxList* (*glob)(void* env, LuxString pattern);");
         self.writeln("    void* env;");
         self.writeln("} LuxFileHandler;");
         self.writeln("");
@@ -1386,6 +1387,23 @@ impl CBackend {
         self.writeln("    return result;");
         self.writeln("}");
         self.writeln("");
+        self.writeln("#include <glob.h>");
+        self.writeln("static LuxList* lux_file_glob(LuxString pattern) {");
+        self.writeln("    LuxList* result = lux_list_new(16);");
+        self.writeln("    glob_t globbuf;");
+        self.writeln("    int ret = glob(pattern, 0, NULL, &globbuf);");
+        self.writeln("    if (ret == 0) {");
+        self.writeln("        for (size_t i = 0; i < globbuf.gl_pathc; i++) {");
+        self.writeln("            size_t len = strlen(globbuf.gl_pathv[i]);");
+        self.writeln("            LuxString name = (LuxString)lux_rc_alloc(len + 1, LUX_TAG_STRING);");
+        self.writeln("            memcpy(name, globbuf.gl_pathv[i], len + 1);");
+        self.writeln("            lux_list_push(result, (void*)name);");
+        self.writeln("        }");
+        self.writeln("        globfree(&globbuf);");
+        self.writeln("    }");
+        self.writeln("    return result;");
+        self.writeln("}");
+        self.writeln("");
         self.writeln("static LuxString default_file_read(void* env, LuxString path) {");
         self.writeln("    (void)env;");
         self.writeln("    return lux_file_read(path);");
@@ -1431,6 +1449,11 @@ impl CBackend {
         self.writeln("    return lux_file_readDir(path);");
         self.writeln("}");
         self.writeln("");
+        self.writeln("static LuxList* default_file_glob(void* env, LuxString pattern) {");
+        self.writeln("    (void)env;");
+        self.writeln("    return lux_file_glob(pattern);");
+        self.writeln("}");
+        self.writeln("");
         self.writeln("static LuxFileHandler default_file_handler = {");
         self.writeln("    .read = default_file_read,");
         self.writeln("    .write = default_file_write,");
@@ -1441,6 +1464,7 @@ impl CBackend {
         self.writeln("    .mkdir = default_file_mkdir,");
         self.writeln("    .copy = default_file_copy,");
         self.writeln("    .readDir = default_file_readDir,");
+        self.writeln("    .glob = default_file_glob,");
         self.writeln("    .env = NULL");
         self.writeln("};");
         self.writeln("");
@@ -3790,6 +3814,17 @@ impl CBackend {
                             self.register_rc_var(&temp, "LuxList*");
                             return Ok(temp);
                         }
+                        "glob" => {
+                            let pattern = self.emit_expr(&args[0])?;
+                            let temp = format!("_glob_{}", self.fresh_name());
+                            if self.has_evidence {
+                                self.writeln(&format!("LuxList* {} = ev->file->glob(ev->file->env, {});", temp, pattern));
+                            } else {
+                                self.writeln(&format!("LuxList* {} = lux_file_glob({});", temp, pattern));
+                            }
+                            self.register_rc_var(&temp, "LuxList*");
+                            return Ok(temp);
+                        }
                         _ => {}
                     }
                 }
@@ -5353,7 +5388,7 @@ impl CBackend {
                         "read" => Some("LuxString".to_string()),
                         "write" | "append" | "delete" | "mkdir" | "copy" => Some("void".to_string()),
                         "exists" | "isDir" => Some("LuxBool".to_string()),
-                        "readDir" | "listDir" => Some("LuxList*".to_string()),
+                        "readDir" | "listDir" | "glob" => Some("LuxList*".to_string()),
                         _ => None,
                     }
                 } else if effect.name == "Http" {

src/interpreter.rs

@@ -3968,6 +3968,29 @@ impl Interpreter {
                 }
             }
 
+            ("File", "glob") => {
+                let pattern = match request.args.first() {
+                    Some(Value::String(s)) => s.clone(),
+                    _ => return Err(RuntimeError {
+                        message: "File.glob requires a string pattern".to_string(),
+                        span: None,
+                    }),
+                };
+                match glob::glob(&pattern) {
+                    Ok(paths) => {
+                        let entries: Vec<Value> = paths
+                            .filter_map(|entry| entry.ok())
+                            .map(|path| Value::String(path.to_string_lossy().to_string()))
+                            .collect();
+                        Ok(Value::List(entries))
+                    }
+                    Err(e) => Err(RuntimeError {
+                        message: format!("Invalid glob pattern '{}': {}", pattern, e),
+                        span: None,
+                    }),
+                }
+            }
+
             // ===== Process Effect =====
             ("Process", "exec") => {
                 use std::process::Command;

src/types.rs

@@ -964,6 +964,11 @@ impl TypeEnv {
                         ],
                         return_type: Type::Unit,
                     },
+                    EffectOpDef {
+                        name: "glob".to_string(),
+                        params: vec![("pattern".to_string(), Type::String)],
+                        return_type: Type::List(Box::new(Type::String)),
+                    },
                 ],
             },
         );