Last active
April 24, 2017 09:28
-
-
Save aisamanra/3d2305e12a1699aaae0eb1039496389b to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#include <stdio.h> | |
typedef struct { | |
int tag; | |
union { | |
int l; | |
struct { | |
char* fst; | |
float snd; | |
} r; | |
} payload; | |
} either; | |
#define tag_left 1 | |
void | |
mk_left(either *e, int l) | |
{ | |
e->tag = tag_left; | |
e->payload.l = l; | |
} | |
void | |
from_left(either e, void f(int)) | |
{ | |
f(e.payload.l); | |
} | |
#define tag_right 2 | |
void | |
mk_right(either* e, char* r, float f) | |
{ | |
e->tag = tag_right; | |
e->payload.r.fst = r; | |
e->payload.r.snd = f; | |
} | |
void | |
from_right(either e, void f(char*, float)) | |
{ | |
f(e.payload.r.fst, e.payload.r.snd); | |
} | |
#define match(expr) { typeof(expr) _expr = expr; switch(_expr.tag) { | |
#define end_match } } | |
#define case_(constr, bindings) } break; case(tag_##constr): { auto void _handler bindings; from_##constr(_expr, _handler); void _handler bindings | |
int main(int argc, char* argv[]) | |
{ | |
either e1, e2; | |
mk_right(&e1, "argl", 7.0); | |
mk_left(&e2, 22); | |
match(e1) { | |
case_(left, (int n)) { | |
printf("left %d\n", n); | |
} | |
case_(right, (char* s, float f)) { | |
printf("right %s %f\n", s, f); | |
} | |
} end_match; | |
match(e2) { | |
case_(left, (int n)) { | |
printf("left %d\n", n); | |
} | |
case_(right, (char* s, float f)) { | |
printf("right %s %f\n", s, f); | |
} | |
} end_match; | |
return 0; | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment