(defun) and support for functions defined in Lisp

This commit is contained in:
~keith 2022-02-04 15:54:34 +00:00
parent fb3d5b90c6
commit ad98504f4f
Signed by: keith
GPG Key ID: 5BEBEEAB2C73D520
7 changed files with 137 additions and 8 deletions

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@ -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.

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@ -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.

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@ -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);

104
main.c
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@ -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;
}
if (cons->car.value.atom == atom_cond) {
} else if (cons->car.value.atom == atom_cond) {
lisp_sform_cond(cons->cdr.value.cons, value);
return;
}
if (cons->car.value.atom == atom_let) {
} else 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"));

6
main.h
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@ -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

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@ -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);
}

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@ -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