1  // ffi.h
 2  // C interface for Haskell FFI
 3  //
 4  // This header defines the C ABI that Haskell's FFI can call.
 5  // The implementation is in C++ (ffi.cpp) but uses extern "C" linkage.
 6  
 7  #ifndef ALEPH_FFI_H
 8  #define ALEPH_FFI_H
 9  
10  #include <stddef.h>
11  #include <stdint.h>
12  
13  #ifdef __cplusplus
14  extern "C" {
15  #endif
16  
17  // =============================================================================
18  // Simple arithmetic (demonstrates basic FFI)
19  // =============================================================================
20  
21  int32_t ffi_add(int32_t a, int32_t b);
22  int32_t ffi_multiply(int32_t a, int32_t b);
23  
24  // =============================================================================
25  // Vector operations (demonstrates pointer passing)
26  // =============================================================================
27  
28  // Compute dot product of two vectors
29  // Returns the result, vectors are not modified
30  double ffi_dot_product(const double* a, const double* b, size_t len);
31  
32  // Compute L2 norm of a vector
33  double ffi_norm(const double* v, size_t len);
34  
35  // Scale a vector in-place: v[i] *= scalar
36  void ffi_scale(double* v, size_t len, double scalar);
37  
38  // =============================================================================
39  // String operations (demonstrates string passing)
40  // =============================================================================
41  
42  // Returns a greeting string. Caller must free with ffi_free_string.
43  char* ffi_greet(const char* name);
44  
45  // Free a string returned by FFI functions
46  void ffi_free_string(char* str);
47  
48  // =============================================================================
49  // Opaque handle pattern (demonstrates resource management)
50  // =============================================================================
51  
52  // Opaque handle to a Counter object
53  typedef struct Counter Counter;
54  
55  // Create a new counter with initial value
56  Counter* ffi_counter_new(int32_t initial);
57  
58  // Destroy a counter
59  void ffi_counter_free(Counter* counter);
60  
61  // Get current value
62  int32_t ffi_counter_get(const Counter* counter);
63  
64  // Increment and return new value
65  int32_t ffi_counter_increment(Counter* counter);
66  
67  // Add n and return new value
68  int32_t ffi_counter_add(Counter* counter, int32_t n);
69  
70  #ifdef __cplusplus
71  }
72  #endif
73  
74  #endif // ALEPH_FFI_H