1 files changed, 149 insertions, 0 deletions
diff --git a/src/primitives.c b/src/primitives.c
new file mode 100644
index 0000000..9554fb6
--- /dev/null
+++ b/src/primitives.c
@@ -0,0 +1,149 @@
+#include "primitives.h"
+#include "sexp.h"
+
+SExpRef primitive_if(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) != 3) goto error;
+    SExpRef cond = CAR(args);
+    SExpRef tb = CADR(args);
+    SExpRef fb = CADDR(args);
+    cond = EVAL(cond);
+    if (ERRORP(cond)) return cond;
+    if (TRUEP(cond)) return EVAL(tb);
+    else return EVAL(fb);
+    return NIL;
+error:
+    return new_error(interp, "if: syntax error.\n");
+}
+
+SExpRef primitive_cond(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) < 1) goto error;
+    SExpRef iter = args;
+    while (!NILP(iter)) {
+        SExpRef pair = CAR(iter);
+        if (!lisp_check_list(interp, pair)) goto error;
+        if (lisp_length(interp, pair) != 2) goto error;
+        SExpRef condition = CAR(pair);
+        SExpRef exp = CADR(pair);
+        condition = EVAL(condition);
+        if (ERRORP(condition)) return condition;
+        if (TRUEP(condition)) return EVAL(exp);
+        iter = CDR(iter);
+    }
+    return NIL;
+error:
+    return new_error(interp, "cond: syntax error.\n");
+}
+
+SExpRef primitive_progn(Interp *interp, SExpRef args) {
+    SExpRef iter = args;
+    SExpRef ret;
+    while (!NILP(iter)) {
+        ret = EVAL(CAR(iter));
+        if (ERRORP(ret)) return ret;
+        iter = CDR(iter);
+    }
+    return ret;
+}
+
+SExpRef primitive_setq(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) != 2) goto error;
+    SExpRef name = CAR(args);
+    SExpRef exp = CADR(args);
+    if (REF(name)->type != kSymbolSExp) goto error;
+    SExpRef value = EVAL(exp);
+    if (ERRORP(value)) return value;
+    return lisp_setq(interp, REF(name)->str, value);
+error:
+    return new_error(interp, "setq: syntax error.\n");
+}
+
+static const char *binding_name(Interp *interp, SExpRef binding) {
+    SExpRef namesym = REF(binding)->binding.name;
+    return REF(namesym)->str;
+}
+
+static bool is_binding_repeat(Interp *interp, SExpRef sym, SExpRef env) {
+    SExpRef binding = REF(env)->env.bindings;
+    while (!NILP(binding)) {
+        if (strcmp(REF(sym)->str, binding_name(interp, binding)) == 0) return true;
+        binding = REF(binding)->binding.next;
+    }
+    return false;
+}
+
+SExpRef primitive_let(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) < 1) goto error;
+    SExpRef bindings = CAR(args);
+    SExpRef env = new_env(interp);
+    REF(env)->env.parent = CAR(interp->stack);
+
+    SExpRef iter = bindings;
+    while (!NILP(iter)) {
+        SExpRef x = CAR(iter);
+        if (!lisp_check_list(interp, x)) goto error;
+        if (lisp_length(interp, x) != 2) goto error;
+        if (REF(CAR(x))->type != kSymbolSExp) goto error;
+        if (is_binding_repeat(interp, CAR(x), env)) goto error;
+        SExpRef binding = new_binding(interp, CAR(x), NIL);
+        REF(binding)->binding.next = REF(env)->env.bindings;
+        REF(env)->env.bindings = binding;
+        iter = CDR(iter);
+    }
+    interp->stack = CONS(env, interp->stack);
+
+    SExpRef ret = NIL;
+    iter = bindings;
+    while (!NILP(iter)) {
+        SExpRef x = CAR(iter);
+        SExpRef val = EVAL(CADR(x));
+        if (REF(val)->type == kErrSExp) goto end;
+        ret = lisp_setq(interp, REF(CAR(x))->str, val);
+        if (ERRORP(ret)) goto end;
+        iter = CDR(iter);
+    }
+
+    SExpRef body = CDR(args);
+    iter = body;
+    while (!NILP(iter)) {
+        SExpRef exp = CAR(iter);
+        ret = EVAL(exp);
+        if (REF(ret)->type == kErrSExp) goto end;
+        iter = CDR(iter);
+    }
+end:
+    interp->stack = CDR(interp->stack);
+    return ret;
+
+error:
+    return new_error(interp, "let: syntax error. \n");
+}
+
+SExpRef primitive_while(Interp *interp, SExpRef args) {
+    if (lisp_length(interp, args) < 2) goto error;
+    SExpRef ret = NIL;
+    SExpRef pred = CAR(args);
+    SExpRef body = CDR(args);
+    while (1) {
+        SExpRef cond = EVAL(pred);
+        if (ERRORP(cond)) return cond;
+        if (!TRUEP(cond)) return ret;
+        SExpRef iter = body;
+        while (!NILP(iter)) {
+            SExpRef x = CAR(iter);
+            ret = EVAL(x);
+            if (ERRORP(ret)) return ret;
+            iter = CDR(iter);
+        }
+    }
+error:
+    return new_error(interp, "while: syntax error.\n");
+}
+// TODO:
+// - while
+// - lambda
+// - defun
+// - funcall
+// - apply
+// - defvar
+// - defmacro
+// - macroexpand-1