From 79c2b417c2bcc3a76f1d4be816c2f7534c27cbca Mon Sep 17 00:00:00 2001
From: Able <abl3theabove@gmail.com>
Date: Thu, 4 Nov 2021 22:58:40 -0500
Subject: [PATCH] Result impl and example

---
 main.c | 16 ++++++++++++++++
 rust.h | 23 ++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/main.c b/main.c
index f1f3577..7d1036b 100644
--- a/main.c
+++ b/main.c
@@ -6,3 +6,19 @@ fn(main(), int) {
    print("Hello, World!\n", a);
    Ok();
 }
+
+typedef const char *ErrString;
+typedef void *MemHandle;
+Result_impl(MemHandle, ErrString)
+Result_unwrap_impl(MemHandle, ErrString)
+fn (gimmy_memory(size_t n_bytes), Result(MemHandle, ErrString)){
+    Result(MemHandle, ErrString) possible =
+        {.is_valid = true, .data = malloc(n_bytes)};
+
+    if (!possible.data)
+    {
+        possible.is_valid = false;
+        possible.err = "memory allocation failure";
+    }
+    return possible;
+}
diff --git a/rust.h b/rust.h
index a3aa732..45717a0 100644
--- a/rust.h
+++ b/rust.h
@@ -1,6 +1,6 @@
 #include <stdbool.h>
 #include <stdio.h>
-
+#include <stdlib.h>
 
 #define fn(decl, type) type decl
 #define let(decl, type) const type decl
@@ -12,3 +12,24 @@
 #define Err(); return 1
 
 #define enum union
+
+// Rust like return impl
+#define Result_impl(T, E) \
+typedef struct { \
+    bool is_valid; \
+    union { \
+        T data; \
+        E err; \
+    }; \
+} Result_##T##_##E;
+
+#define Result(T, E) Result_##T##_##E
+
+#define Result_unwrap_impl(T, E) \
+T Result_##T##_unwrap (Result(T, E) result) { \
+    if (result.is_valid) \
+        return result.data; \
+\
+    fprintf(stderr, "%s\n", result.err); \
+    exit(1); \
+}