(defun) and support for functions defined in Lisp

doc/stdlib_forms.md

@@ -4,13 +4,13 @@ other S-expressions.
 
 ## `quote`
 ```
-quote form
+(quote form)
 ```
 `quote` returns `form` as-is, without performing any evaluation on it.
 
 ## `cond`
 ```
-cond {(test {body-form}*)}*
+(cond {(test {body-form}*)}*)
 ```
 `cond` is Keithlisp's basic conditional operator. It consists of zero or
 more clauses (a `test`, followed by zero or more `body-form`s).
@@ -23,7 +23,7 @@ or no clauses were given, `cond` returns nil.
 
 ## `let`
 ```
-let ({var | (var value)}*) {body-form}*
+(let ({var | (var value)}*) {body-form}*)
 ```
 `let` defines locally scoped variables in Keithlisp. It consists of a
 list of variable definitions, followed by zero or more `body-form`s.
@@ -39,3 +39,15 @@ the last one. Before returning, it removes the topmost entry for each
 local variable from the syms-alist. **If a locally scoped entry was
 removed manually, the outer scope's corresponding entry will be removed
 if it exists.**
+
+## `defun`
+
+```
+(defun ({arg}*) {body-form}*)
+```
+`defun` defines a new function in Keithlisp. It consists of a list of
+argument definitions, followed by zero or more `body-form`s.
+
+An argument definition is simply the name of the locally scoped variable
+which it should be bound to. `&optional`, `&rest`, and `&key` arguments
+are not yet supported.

doc/stdlib_internals.md

@@ -27,3 +27,11 @@ currently defined function.
 original string of every atom that Keithlisp has parsed. It returns nil
 if the atoms-alist has been disabled.
 
+## `fun-set!`
+```
+(fun-set! name value)
+```
+`fun-set!` directly modifies the funs-alist, creating a new association
+defining `name` as `value`. It returns the entry it has created. This is
+more or less the equivalent of `set` for function definitions.
+

lisp_string.h

@@ -16,7 +16,7 @@ __attribute__((always_inline)) static inline char* lisp_string_data(lisp_string*
 char* lisp_string_create(char* str);
 char* lisp_string_create_raw(char* buf, int len);
 char* lisp_string_alloc(int len);
-char* lisp_string_copy(lisp_string* lstr);
+lisp_string* lisp_string_copy(lisp_string* lstr);
 int lisp_string_cmp(lisp_string* a_lstr, lisp_string* b_lstr);
 void lisp_string_print(lisp_string* lstr);
 

main.c

@@ -212,6 +212,16 @@ lisp_atom lisp_defun_native(lisp_string* lstr, lisp_native_fun funptr) {
 	return atom;
 }
 
+lisp_cons* lisp_defun_lisp_fun(lisp_atom atom, lisp_cons* fun) {
+	lisp_cons* cons = dbg_malloc(sizeof(lisp_cons));
+	cons->car.type = LISP_T_ATOM;
+	cons->car.value.atom = atom;
+	cons->cdr.type = LISP_T_CONS;
+	cons->cdr.value.cons = fun;
+	lisp_alist_put(&funs_alist, cons);
+	return cons;
+}
+
 void lisp_evaluate_value(lisp_value input, lisp_value* result) {
 	if (input.type == LISP_T_ATOM) {
 		if (input.value.atom == atom_t) {
@@ -233,18 +243,22 @@ void lisp_evaluate_value(lisp_value input, lisp_value* result) {
 void lisp_evaluate(lisp_cons* cons, lisp_value* value) {
 	value->type = LISP_T_CONS;
 	value->value.cons = NULL;
+
+	// can't use a switch here
 	if (cons->car.value.atom == atom_quote) {
 		*value = cons->cdr.value.cons->car;
 		return;
-	}
+	} else if (cons->car.value.atom == atom_cond) {
-	if (cons->car.value.atom == atom_cond) {
 		lisp_sform_cond(cons->cdr.value.cons, value);
 		return;
-	}
+	} else if (cons->car.value.atom == atom_let) {
-	if (cons->car.value.atom == atom_let) {
 		lisp_sform_let(cons->cdr.value.cons, value);
 		return;
+	} else if (cons->car.value.atom == atom_defun) {
+		lisp_sform_defun(cons->cdr.value.cons, value);
+		return;
 	}
+
 	lisp_cons* fun_cons = lisp_alist_get(funs_alist, cons->car);
 	if (fun_cons == NULL) {
 		fprintf(stderr, "EVAL ERROR! (no such fun)\n");
@@ -276,6 +290,9 @@ void lisp_evaluate(lisp_cons* cons, lisp_value* value) {
 			dbg_free(args);
 			args = args_tail;
 		}
+	} else if (fun_cons->cdr.type == LISP_T_CONS) {
+		// lisp-fun
+		lisp_evaluate_lisp_fun(fun_cons->cdr.value.cons, args, value);
 	} else {
 		fprintf(stderr, "EVAL ERROR! (not a native-fun)\n");
 		return;
@@ -344,6 +361,84 @@ void lisp_sform_let(lisp_cons* cons, lisp_value* value) {
 		vars_head = vars_head->cdr.value.cons;
 	}
 }
+lisp_atom atom_defun;
+void lisp_sform_defun(lisp_cons* cons, lisp_value* value) {
+	lisp_atom fun_name = cons->car.value.atom;
+	lisp_cons* fun_data = recursive_copy(cons->cdr.value.cons);
+
+	lisp_defun_lisp_fun(fun_name, fun_data);
+	value->type = LISP_T_CONS;
+	value->value.cons = fun_data;
+}
+
+lisp_cons* recursive_copy(lisp_cons* cons) {
+	lisp_cons* new_cons = dbg_malloc(sizeof(lisp_cons));
+	lisp_cons* new_root = new_cons;
+	while (cons != NULL) {
+		new_cons->car = cons->car;
+		new_cons->cdr = cons->cdr;
+
+		if (cons->car.type == LISP_T_STRING)
+			new_cons->car.value.string = lisp_string_copy(cons->car.value.string);
+		else if (cons->car.type == LISP_T_CONS)
+			new_cons->car.value.cons = recursive_copy(cons->car.value.cons);
+
+		if (cons->cdr.type == LISP_T_STRING)
+			new_cons->cdr.value.string = lisp_string_copy(cons->cdr.value.string);
+
+		if (cons->cdr.type == LISP_T_CONS && cons->cdr.value.cons != NULL) {
+			cons = cons->cdr.value.cons;
+			new_cons->cdr.value.cons = dbg_malloc(sizeof(lisp_cons));
+			new_cons = new_cons->cdr.value.cons;
+		} else {
+			cons = NULL;
+		}
+	}
+	return new_root;
+}
+
+void lisp_evaluate_lisp_fun(lisp_cons* fun, lisp_cons* args, lisp_value* value) {
+	// allocate local vars
+	lisp_cons* head = fun->car.value.cons;
+	while (head != NULL) {
+		// create cons pair for new var
+		lisp_cons* pair = dbg_malloc(sizeof(lisp_cons));
+		pair->car.type = LISP_T_ATOM;
+		pair->car.value.atom = head->car.value.atom;
+		pair->cdr = args->car;
+		args = args->cdr.value.cons;
+		// add to alist
+		lisp_cons* new_alist = dbg_malloc(sizeof(lisp_cons));
+		new_alist->car.type = LISP_T_CONS;
+		new_alist->car.value.cons = pair;
+		new_alist->cdr.type = LISP_T_CONS;
+		new_alist->cdr.value.cons = syms_alist;
+		syms_alist = new_alist;
+
+		head = head->cdr.value.cons;
+	}
+
+	// evaluate body
+	head = fun->cdr.value.cons;
+	while (head != NULL) {
+		lisp_evaluate_value(head->car, value);
+		head = head->cdr.value.cons;
+	}
+
+	// delete local vars
+	head = fun->car.value.cons;
+	while (head != NULL) {
+		lisp_value key;
+		if (head->car.type == LISP_T_CONS)
+			key = head->car.value.cons->car;
+		else
+			key = head->car;
+		lisp_cons* pair = lisp_alist_del(&syms_alist, key);
+		dbg_free(pair);
+
+		head = head->cdr.value.cons;
+	}
+}
 
 lisp_atom atom_cons;
 lisp_atom atom_atom;
@@ -362,6 +457,7 @@ int main() {
 
 	atom_cond = lisp_atom_init(lisp_string_create("cond"));
 	atom_let = lisp_atom_init(lisp_string_create("let"));
+	atom_defun = lisp_atom_init(lisp_string_create("defun"));
 
 	atom_cons = lisp_atom_init(lisp_string_create("cons"));
 	atom_atom = lisp_atom_init(lisp_string_create("atom"));

main.h

@@ -54,6 +54,7 @@ void print_cons(lisp_cons* cons);
 void print_value(lisp_value value);
 
 lisp_atom lisp_defun_native(lisp_string* lstr, lisp_native_fun funptr);
+lisp_cons* lisp_defun_lisp_fun(lisp_atom atom, lisp_cons* fun);
 
 void lisp_evaluate_value(lisp_value input, lisp_value* result);
 void lisp_evaluate(lisp_cons* cons, lisp_value* value);
@@ -61,5 +62,10 @@ extern lisp_atom atom_cond;
 void lisp_sform_cond(lisp_cons* cons, lisp_value* value);
 extern lisp_atom atom_let;
 void lisp_sform_let(lisp_cons* cons, lisp_value* value);
+extern lisp_atom atom_defun;
+void lisp_sform_defun(lisp_cons* cons, lisp_value* value);
+lisp_cons* recursive_copy(lisp_cons* cons);
+
+void lisp_evaluate_lisp_fun(lisp_cons* fun, lisp_cons* args, lisp_value* value);
 
 #endif

native_funs.c

@@ -641,6 +641,11 @@ void lispf_internals_atoms_alist(lisp_cons* cons, lisp_value* value) {
 	value->value.cons = atoms_alist;
 }
 
+void lispf_internals_fun_set(lisp_cons* cons, lisp_value* value) {
+	value->type = LISP_T_CONS;
+	value->value.cons = lisp_defun_lisp_fun(cons->car.value.atom, cons->cdr.value.cons->car.value.cons);
+}
+
 void init_native_funs() {
 	// arithmetic
 	lisp_defun_native(lisp_string_create("+"), &lispf_add);
@@ -692,4 +697,5 @@ void init_native_funs() {
 	lisp_defun_native(lisp_string_create("syms-alist!"), &lispf_internals_syms_alist);
 	lisp_defun_native(lisp_string_create("funs-alist!"), &lispf_internals_funs_alist);
 	lisp_defun_native(lisp_string_create("atoms-alist!"), &lispf_internals_atoms_alist);
+	lisp_defun_native(lisp_string_create("fun-set!"), &lispf_internals_fun_set);
 }

native_funs.h

@@ -51,6 +51,7 @@ void lispf_print(lisp_cons* cons, lisp_value* value);
 void lispf_internals_syms_alist(lisp_cons* cons, lisp_value* value);
 void lispf_internals_funs_alist(lisp_cons* cons, lisp_value* value);
 void lispf_internals_atoms_alist(lisp_cons* cons, lisp_value* value);
+void lispf_internals_fun_set(lisp_cons* cons, lisp_value* value);
 
 void init_native_funs();
 #endif