Add @stdlib/onnx module for local ONNX Runtime inference

CLAUDE.md

@@ -554,7 +554,7 @@ Typed arrays: `let nums: array<i32> = [1, 2, 3];`
 
 ---
 
-## Standard Library (42 modules)
+## Standard Library (43 modules)
 
 Import with `@stdlib/` prefix:
 ```hemlock
@@ -589,6 +589,7 @@ import { TcpStream, UdpSocket } from "@stdlib/net";
 | `logging` | Logger with levels |
 | `math` | sin, cos, sqrt, pow, rand, PI, E |
 | `net` | TcpListener, TcpStream, UdpSocket |
+| `onnx` | ONNX Runtime inference (local ML models) |
 | `os` | platform, arch, cpu_count, hostname |
 | `path` | File path manipulation |
 | `process` | fork, exec, wait, kill |
@@ -979,7 +980,7 @@ make parity
 - Manual memory management with `talloc()` and `sizeof()`
 - Async/await with true pthread parallelism
 - Atomic operations for lock-free concurrent programming
-- 42 stdlib modules (+ arena, assert, semver, toml, retry, iter, random, shell, termios, vector)
+- 43 stdlib modules (+ arena, assert, semver, toml, retry, iter, random, shell, termios, vector, onnx)
 - FFI for C interop with `export extern fn` for reusable library wrappers
 - FFI struct support in compiler (pass C structs by value)
 - FFI pointer helpers (`ptr_null`, `ptr_read_*`, `ptr_write_*`)

Makefile

@@ -35,6 +35,14 @@ ifeq ($(shell uname),Darwin)
     else
         HAS_LIBWEBSOCKETS := 0
     endif
+
+    # On macOS, check for ONNX Runtime
+    BREW_ONNXRUNTIME := $(shell brew --prefix onnxruntime 2>/dev/null)
+    ifneq ($(BREW_ONNXRUNTIME),)
+        HAS_ONNXRUNTIME := $(shell test -f $(BREW_ONNXRUNTIME)/lib/libonnxruntime.dylib && echo 1 || echo 0)
+    else
+        HAS_ONNXRUNTIME := 0
+    endif
 else
     # On Linux, use pkg-config if available
     LIBFFI_CFLAGS := $(shell pkg-config --cflags libffi 2>/dev/null)
@@ -48,6 +56,9 @@ else
 
     # Check if libwebsockets is available on Linux
     HAS_LIBWEBSOCKETS := $(shell pkg-config --exists libwebsockets 2>/dev/null && echo 1 || (test -f /usr/include/libwebsockets.h && echo 1 || echo 0))
+
+    # Check if ONNX Runtime is available on Linux
+    HAS_ONNXRUNTIME := $(shell pkg-config --exists libonnxruntime 2>/dev/null && echo 1 || (test -f /usr/local/include/onnxruntime_c_api.h && echo 1 || (test -f /usr/include/onnxruntime/core/session/onnxruntime_c_api.h && echo 1 || echo 0)))
 endif
 
 # Base libraries (always required)
@@ -177,6 +188,17 @@ else
 	$(CC) -shared -fPIC -o stdlib/c/libffi_struct_test.so stdlib/c/ffi_struct_test.c
 endif
 	@echo "✓ libffi_struct_test built successfully"
+ifeq ($(HAS_ONNXRUNTIME),1)
+	@echo "Building stdlib/c/libhemlock_onnx..."
+ifeq ($(shell uname),Darwin)
+	$(CC) -shared -fPIC -I$(BREW_ONNXRUNTIME)/include -o stdlib/c/libhemlock_onnx.dylib stdlib/c/onnx_wrapper.c -L$(BREW_ONNXRUNTIME)/lib -lonnxruntime
+else
+	$(CC) -shared -fPIC -o stdlib/c/libhemlock_onnx.so stdlib/c/onnx_wrapper.c -lonnxruntime
+endif
+	@echo "✓ libhemlock_onnx built successfully"
+else
+	@echo "⊘ Skipping libhemlock_onnx (libonnxruntime not installed)"
+endif
 
 # Clean stdlib builds
 .PHONY: stdlib-clean

stdlib/c/README.md

@@ -50,12 +50,45 @@ statically linked into the Hemlock interpreter. No separate FFI wrapper is neede
 
 The `lws_wrapper.so` is primarily used for WebSocket functionality.
 
+## ONNX Runtime Wrapper
+
+### Purpose
+
+`onnx_wrapper.c` provides a flat C interface to ONNX Runtime's `OrtApi` struct-of-function-pointers,
+enabling Hemlock's FFI system to call ONNX Runtime functions directly.
+
+### Requirements
+
+```bash
+# From GitHub releases
+wget https://github.com/microsoft/onnxruntime/releases/download/v1.17.0/onnxruntime-linux-x64-1.17.0.tgz
+tar xzf onnxruntime-linux-x64-1.17.0.tgz
+sudo cp lib/libonnxruntime.so* /usr/local/lib/
+sudo cp -r include/* /usr/local/include/
+sudo ldconfig
+
+# macOS
+brew install onnxruntime
+```
+
+### Building
+
+```bash
+# From hemlock root directory
+make stdlib
+```
+
+This compiles `onnx_wrapper.c` → `libhemlock_onnx.so`
+
+### Usage
+
+Used by `@stdlib/onnx` (`stdlib/onnx.hml`) for local ML inference.
+
 ## Future C Modules
 
 Planned FFI wrappers:
 - OpenSSL wrapper for crypto functions
 - zlib wrapper for compression
-- SQLite wrapper for embedded database
 
 ## Design Philosophy