From b8bad3bf5af3261f25780a8cd8b90a659fe29bab Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 13 Oct 2021 14:19:32 +0200
Subject: Add support for environments and recursive evaluation

---
 src/bootstrap/objects.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 107 insertions(+), 2 deletions(-)

(limited to 'src/bootstrap/objects.c')

diff --git a/src/bootstrap/objects.c b/src/bootstrap/objects.c
index 9acbcd9..30827f1 100644
--- a/src/bootstrap/objects.c
+++ b/src/bootstrap/objects.c
@@ -9,6 +9,8 @@ typedef enum ObjectType {
     OBJ_TYPE_ERR,
 } ObjectType;
 
+struct Environment;
+
 typedef struct Object {
     ObjectType type;
     union {
@@ -34,7 +36,7 @@ typedef struct Object {
         };
 
         // OBJ_TYPE_PROCEDURE
-        struct Object *(*proc)(struct Object *args);
+        struct Object *(*proc)(struct Environment *env, struct Object *args);
     };
 } Object;
 
@@ -66,7 +68,7 @@ make_fixnum(ssize_t num) {
 }
 
 Object *
-make_procedure(Object *(*proc)(struct Object *args)) {
+make_procedure(Object *(*proc)(struct Environment *, struct Object *args)) {
     Object *obj = alloc_object(OBJ_TYPE_PROCEDURE);
     obj->proc = proc;
     return obj;
@@ -195,3 +197,106 @@ display(Object *root) {
     }
     return;
 }
+
+#include "environment.c"
+
+Object *
+eval(Environment* env, Object *root) {
+    switch (root->type) {
+        case OBJ_TYPE_FIXNUM:
+        case OBJ_TYPE_BOOL:
+        case OBJ_TYPE_NIL:
+        case OBJ_TYPE_STRING: {
+            return root;
+        } break;
+        case OBJ_TYPE_SYMBOL: {
+            Object *val = env_lookup(env, root);
+            if (val == obj_err) {
+                error_push((Error){
+                    .type = ERR_TYPE_RUNTIME,
+                    .value = ERR_SYMBOL_NOT_FOUND,
+                });
+                return obj_err;
+            }
+            return val;
+        } break;
+        case OBJ_TYPE_PAIR: {
+            if (root->car->type == OBJ_TYPE_SYMBOL) {
+                Object *val = env_lookup(env, root->car);
+                if (val == obj_err) {
+                    error_push((Error){
+                        .type = ERR_TYPE_RUNTIME,
+                        .value = ERR_SYMBOL_NOT_FOUND,
+                    });
+                    return obj_err;
+                }
+                if (val->type == OBJ_TYPE_PROCEDURE) {
+                    return val->proc(env, root->cdr);
+                }
+                error_push((Error){
+                    .type = ERR_TYPE_RUNTIME,
+                    .value = ERR_OBJ_NOT_CALLABLE,
+                });
+                return obj_err;
+            }
+        } break;
+        default: {
+            break;
+        } break;
+    }
+
+    error_push((Error){
+        .type = ERR_TYPE_RUNTIME,
+        .value = ERR_UNKNOWN_OBJ_TYPE,
+    });
+    return obj_err;
+}
+
+Object *
+proc_quote(Environment *env, Object *obj) {
+    (void)env;
+    return obj->car;
+}
+
+Object *
+proc_sum(Environment *env, Object *obj) {
+    // First argument.
+    if (obj == obj_nil) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_NOT_ENOUGH_ARGS,
+        });
+        return obj_err;
+    }
+    Object *car = eval(env, obj->car);
+    if (car == obj_err) {
+        return obj_err;
+    }
+    if (car->type != OBJ_TYPE_FIXNUM) {
+        error_push((Error){
+            .type = ERR_TYPE_RUNTIME,
+            .value = ERR_WRONG_ARG_TYPE,
+        });
+        return obj_err;
+    }
+
+    // Traverse the list.
+    obj = obj->cdr;
+    ssize_t tot = car->fixnum;
+    while (obj->type == OBJ_TYPE_PAIR) {
+        Object *car = eval(env, obj->car);
+        if (car == obj_err) {
+            return obj_err;
+        }
+        if (car->type != OBJ_TYPE_FIXNUM) {
+            error_push((Error){
+                .type = ERR_TYPE_RUNTIME,
+                .value = ERR_WRONG_ARG_TYPE,
+            });
+            return obj_err;
+        }
+        tot += car->fixnum;
+        obj = obj->cdr;
+    }
+    return make_fixnum(tot);
+}
-- 
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