use racket lang for the body of macros?

[phoniz]

granted I am new to racket, but I'd like to use the racket string operations in the body of a macro, say for generating structs and their construction functions?

I would like a macro

(-> v x 10)

That when evaluated emits C++ like

v->x = 10;

I tried using format but the emitted code is

format("~a->~a = ~a",v,x,x);

[phoniz]

I was able to generate

struct Vec { double x, y, z; };
Vec* mk_vec(double x,double y,double z) {
Vec *v = new Vec();
v->x = x;
v->y = y;
v->z = z;
return v;}

from

(code "struct Vec { double x, y, z; }" )

(defn "Vec*" mk_vec ("double x" "double y" "double z")
    (code "Vec *v = new Vec()")
    (-> v x x)
    (-> v y y)
    (-> v z z)
    (return v))

by adding

[(->) (format "~a->~a = ~a" (compile-expr (list-ref e 1)) (compile-expr (list-ref e 2)) (compile-expr (list-ref e 3)))]

Into compile-expr but I would like to add operators using macros. Currently reading about syntax-case

[Taegyoon Kim]

In L++ 0.2.6, it became possible via defmacro.

L++ Compiler 0.2.6 (C) 2014 KIM Taegyoon
Enter code (EOF when done):
(defmacro -> (var field value)
  `(code ,(format "~a->~a=~a" var field value)))

(code "struct Vec { double x, y, z; }" )

(defn "Vec*" mk_vec ("double x" "double y" "double z")
    (code "Vec *v = new Vec()")
    (-> v x x)
    (-> v y y)
    (-> v z z)
    (return v))
(main)
Compiled:
#include <iostream>
;
struct Vec { double x, y, z; };
Vec* mk_vec(double x,double y,double z) {
Vec *v = new Vec();
v->x=x;
v->y=y;
v->z=z;
return v;}
;
int main(int argc, char **argv) {
;
return 0;};

Current directory: C:\Users\art\Documents\proj\l++\
Output written to: a-out.cpp
Binary written to: a-out
#t

However, (-> v z (+ z 1.0)) doesn't work for now.

[Taegyoon Kim]

I think this issue is solved now.

In L++ 0.2.7, it became possible via define-syntax-rule and format.

L++ Compiler 0.2.7 (C) 2014 KIM Taegyoon
Enter code (EOF when done):
(define-syntax-rule (-> var field value)
  (format "~a->~a=~a" var field value))

(code "struct Vec { double x, y, z; }" )

(defn "Vec*" mk_vec ("double x" "double y" "double z")
    (code "Vec *v = new Vec()")
    (-> v x x)
    (-> v y y)
    (-> v z z)
    (-> v z (+ z 1.0))
    (return v))
(main)
Compiled:
#include <iostream>
;
struct Vec { double x, y, z; };
Vec* mk_vec(double x,double y,double z) {
Vec *v = new Vec();
v->x=x;
v->y=y;
v->z=z;
v->z=(z+1.0);
return v;}
;
int main(int argc, char **argv) {
;
return 0;};

Current directory: C:\Users\art\Documents\proj\l++\
Output written to: a-out.cpp
Binary written to: a-out
#t

As you see, (-> v z (+ z 1.0)) works now.

[phoniz]

excellent!