Move variable setting code into utilities.

The '.' operator now represents method calls. A function f: (a, b)->c
can be called as a.f(b), which is equivalent to f(a, b). Besides
this change, all reserved operators now have a negative precedence
(it's relative, remember?), and some function names were changed.

README.md

@@ -0,0 +1,74 @@
+# libabacus
+A math-centered programming language library.
+
+## About
+libabacus is effectively a stripped down, embeddable programming language.
+It relies on the program it's embedded into to provide the standard library. In fact,
+it doesn't even provide an underlying implementation for numbers - the client code
+provides a means of convering a string into a number, and a way of freeing that value.
+libabacus takes care of the rest. The features of libabacus are geared towards 
+calculators, so it does not provide higher-level abstractions like OOP.
+
+## Syntax
+libabacus has fairly simple syntax. A simple number expression is
+```
+42
+```
+If an operator `+` is registered with libabacus, then an expression using
+that operator looks like
+```
+21+21
+```
+If two functions, `f` and `g` are registered with libabacus, where `f` takes
+one argument and `g` takes two, then the syntax for calling these functions is
+```
+f(42)
+g(21, 21)
+```
+Blocks are a way to combine a sequence of expressions into one. The value of a block
+is the result of the last expression in that block. Expressions are delimited by the
+`;` character. For example,
+```
+{ 3; 2; 1 }
+```
+evalutes to `1`. Blocks are the first bit of syntax we've seen that can evalute to
+a value that isn't a number. For instance, the empty block, `{}`, does not
+evaluate to a number. Instead, it evalutes to `()`. This is a value of the `unit` type,
+which only has one possible value, `()`.
+
+User-defined functions are supported by libabacus:
+```
+fun square(a: num): num { a*a }
+```
+Let's pick this apart. The first part of a function declaration is the `fun` keyword. The name
+of the function is next, followed by the list of parameters that this function accepts. Parameters
+are listed in the form `[name]:[type]`. The return type of the function must also be specified.
+Lastly, the block used to evaluate the function is needed. 
+
+The block captures the scope in which the function was declared. For instance, in the following piece of code,
+```
+a = 0;
+fun test(): num { 
+    a = a + 1
+}
+```
+`test` actually has access to `a`, and calling `test` many times will yield increasing values of a.
+
+Although all parameters must specify a type, this type can be
+arbitrary to allow for polymorphic functions. For instance, a function to apply another function to an argument
+twice can be written as:
+```
+fun apply_twice(func: ('T)->'T, a: 'T): 'T {
+    func(a);
+    func(a)
+}
+```
+
+## Integration
+Everything in libabacus revolves around the `libab` struct. This struct is used to keep all the state related to the evaluation,
+and also contains the garbage collector. It needs to be instantiated using the `libab_init` function.
+```C
+libab ab;
+libab_init(&ab, parse_function, free_function);
+```
+Please see `interactive.c` for an example of a simple yet complete implementation.

include/custom.h

@@ -135,8 +135,9 @@ void libab_behavior_free(libab_behavior* behavior);
  * @param associativity the associativity (left = -1, right = 1) of the
  * operator.
  * @param function the function this operator represents.
+ * @result the result of the initialization.
  */
-void libab_operator_init(libab_operator* op, libab_operator_variant variant,
+libab_result libab_operator_init(libab_operator* op, libab_operator_variant variant,
                          int precedence, int associativity, const char* function);
 /**
  * Frees the given operator.

include/interpreter.h

@@ -70,11 +70,25 @@ libab_result libab_interpreter_run(libab_interpreter* intr, libab_tree* tree,
  * @param into the reference to store the result into.
  * @return the result of the call.
  */
-libab_result libab_interpreter_run_function(libab_interpreter* intr,
+libab_result libab_interpreter_call_function(libab_interpreter* intr,
                                             libab_ref* scope,
                                             const char* function,
                                             libab_ref_vec* params,
                                             libab_ref* into);
+/**
+ * Calls a function value with the given parameters.
+ * @param intr the interpreter to use to call the function.
+ * @param scope the scope in which the function should be searched for.
+ * @param function the function to call.
+ * @param params the parameters to pass to the function.
+ * @param into the reference to store the result into.
+ * @return the result of the call.
+ */
+libab_result libab_interpreter_call_value(libab_interpreter* intr,
+                                         libab_ref* scope,
+                                         libab_ref* function,
+                                         libab_ref_vec* params,
+                                         libab_ref* into);
 /**
  * Gets the unit value from this interpreter.
  * @param intr the interpreter from which to get the unit value.

include/libabacus.h

@@ -232,6 +232,13 @@ void libab_get_false_value(libab* ab, libab_ref* into);
  */
 void libab_get_bool_value(libab* ab, int val, libab_ref* into);
 
+/**
+ * Parses the given piece of code using the given libabacus instance.
+ * @param ab the instance to use to parse the code.
+ * @param string the source code to parse.
+ * @param into the value to store the newly parsed tree into.
+ */
+libab_result libab_parse(libab* ab, const char* string, libab_tree** into);
 /**
  * Executes the given string of code.
  * @param ab the libabacus instance to use for executing code.
@@ -256,7 +263,7 @@ libab_result libab_run_tree(libab* ab, libab_tree* tree, libab_ref* value);
  * @param param_count the number of parameters given to this function.
  * @return the result of the call.
  */
-libab_result libab_run_function(libab* ab, const char* function,
+libab_result libab_call_function(libab* ab, const char* function,
                                 libab_ref* into,
                                 size_t param_count, ...);
 /**
@@ -286,7 +293,7 @@ libab_result libab_run_tree_scoped(libab* ab, libab_tree* tree, libab_ref* scope
  * @param param_count the number of parameters given to this function.
  * @return the result of the call.
  */
-libab_result libab_run_function_scoped(libab* ab, const char* function, libab_ref* scope,
+libab_result libab_call_function_scoped(libab* ab, const char* function, libab_ref* scope,
                                        libab_ref* into,
                                        size_t param_count, ...);
 

include/refcount_internal.h

@@ -1,8 +0,0 @@
-#ifndef LIBABACUS_REFCOUNT_INTERNAL_H
-#define LIBABACUS_REFCOUNT_INTERNAL_H
-
-#include "refcount.h"
-
-void libab_ref_count_changed(libab_ref_count* count);
-
-#endif

include/util.h

@@ -103,6 +103,28 @@ libab_result libab_create_value_ref(libab* ab, libab_ref* into,
  */
 libab_result libab_create_value_raw(libab* ab, libab_ref* into,
                                     void* data, libab_ref* type);
+/**
+ * Overloads a function of the given name.
+ * @param table the table to insert the function into.
+ * @param name the name of the function.
+ * @param function the function to register.
+ * @return the result of the overload.
+ */
+libab_result libab_overload_function(libab* ab,
+                                     libab_table* table,
+                                     const char* name,
+                                     libab_ref* function);
+/**
+ * Sets a value under the given name, overriding
+ * an existing value if it exists.
+ * @param table the table to store the value into.
+ * @param name the name of the variable.
+ * @param the value of the new variable.
+ * @return the result of setting the variable.
+ */
+libab_result libab_set_variable(libab_table* table,
+                                const char* name,
+                                libab_ref* value);
 /**
  * Allocates a function that uses internal code to run.
  * @param into the reference into which to store the new function.
@@ -187,5 +209,19 @@ void* libab_unwrap_param(libab_ref_vec* vec, size_t index);
  * @param buffer_size the size of the to buffer.
  */
 void libab_sanitize(char* to, const char* from, size_t buffer_size);
+/**
+ * Creates a new instance of libabacus allocated on the heap.
+ * @param into the pointer into which to store the newly allocated libab instance.
+ * @param parse_function the function used to parse numbers.
+ * @param free_function the function used to free parsed numbers.
+ */
+libab_result libab_create_instance(libab** into, 
+                                   void* (*parse_function)(const char*),
+                                   void (*free_function)(void*));
+/**
+ * Destroys the given libabacus instance allocated on the stack.
+ * @param into the reference to destroy.
+ */
+void libab_destroy_instance(libab* into);
 
 #endif

src/custom.c

@@ -1,4 +1,5 @@
 #include "custom.h"
+#include "util.h"
 
 void libab_behavior_init_internal(libab_behavior* behavior,
                                   libab_function_ptr func) {
@@ -15,6 +16,9 @@ void libab_behavior_init_tree(libab_behavior* behavior, libab_tree* tree) {
 void libab_behavior_copy(libab_behavior* behavior, libab_behavior* into) {
     into->variant = behavior->variant;
     into->data_u = behavior->data_u;
+    if(into->variant == BIMPL_TREE) {
+        into->data_u.tree->int_value++;
+    }
 }
 
 void libab_behavior_free(libab_behavior* behavior) {
@@ -23,16 +27,20 @@ void libab_behavior_free(libab_behavior* behavior) {
     }
 }
 
-void libab_operator_init(libab_operator* op, libab_operator_variant variant,
+libab_result libab_operator_init(libab_operator* op, libab_operator_variant variant,
                          int precedence, int associativity, const char* function) {
+    libab_result result = LIBAB_SUCCESS;
+    char* into;
     op->variant = variant;
     op->precedence = precedence;
     op->associativity = associativity;
-    op->function = function;
+    result = libab_copy_string(&into, function);
+    op->function = into;
+    return result;
 }
 
 void libab_operator_free(libab_operator* op) {
-
+    free((char*) op->function);
 }
 
 libab_result _function_init(libab_function* function, libab_ref* scope) {

src/gc.c

@@ -3,7 +3,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <memory.h>
-#include "refcount_internal.h"
 
 void libab_gc_list_init(libab_gc_list* list) {
     memset(&list->head_sentinel, 0, sizeof(list->head_sentinel));

src/interactive.c

@@ -71,13 +71,11 @@ FUNCTION(xor) {
 }
 
 FUNCTION(atan) {
-    printf("atan called\n");
     double* val = libab_unwrap_param(params, 0);
     return create_double_value(ab, atan(*val), into);
 }
 
 FUNCTION(atan2) {
-    printf("atan2 called\n");
     double* left = libab_unwrap_param(params, 0);
     double* right = libab_unwrap_param(params, 1);
     return create_double_value(ab, atan2(*left, *right), into);
@@ -115,7 +113,6 @@ FUNCTION(print_unit) {
         libab_result result = LIBAB_SUCCESS; \
         double right; \
         double left; \
-        printf(#name " called\n"); \
         left = *((double*)libab_unwrap_param(params, 0)); \
         right = *((double*)libab_unwrap_param(params, 1)); \
         create_double_value(ab, expression, into); \
@@ -176,6 +173,7 @@ libab_result register_functions(libab* ab) {
     libab_ref_free(&trig_type);
     libab_ref_free(&atan2_type);
     libab_ref_free(&difficult_type);
+    libab_ref_free(&equals_num_type);
     libab_ref_free(&print_num_type);
     libab_ref_free(&print_unit_type);
     libab_ref_free(&print_bool_type);
@@ -200,7 +198,7 @@ libab_result loop(libab* ab, int interaction_count, libab_ref* scope) {
         if (eval_result != LIBAB_SUCCESS) {
             printf("Invalid input (error code %d).\n", eval_result);
         } else {
-            result = libab_run_function_scoped(ab, "print", scope, &call_into, 1, &eval_into);
+            result = libab_call_function_scoped(ab, "print", scope, &call_into, 1, &eval_into);
             if(result == LIBAB_BAD_CALL) {
                 printf("(?)\n");
                 result = LIBAB_SUCCESS;
@@ -216,7 +214,6 @@ libab_result loop(libab* ab, int interaction_count, libab_ref* scope) {
 int main() {
     libab_result result;
     libab_ref scope;
-    libab_ref test;
     libab ab;
 
     if (libab_init(&ab, impl_parse, impl_free) != LIBAB_SUCCESS) {
@@ -230,8 +227,6 @@ int main() {
     }
     if(result == LIBAB_SUCCESS) {
         loop(&ab, INTERACTIONS, &scope);
-        libab_table_search_value(libab_ref_get(&scope), "test", &test);
-        printf("%p\n", libab_ref_get(&test));
         libab_ref_free(&scope);
     }
 

src/interpreter.c

@@ -623,7 +623,6 @@ libab_result _interpreter_copy_type_offset(libab_ref* type,
     libab_result result = LIBAB_SUCCESS;
     libab_parsetype* new_type;
     libab_parsetype* copy_of = libab_ref_get(type);
-    size_t index = 0;
     if((new_type = malloc(sizeof(*new_type)))) {
         new_type->variant = copy_of->variant;
         new_type->data_u = copy_of->data_u;
@@ -632,9 +631,9 @@ libab_result _interpreter_copy_type_offset(libab_ref* type,
         if(result == LIBAB_SUCCESS) {
             libab_ref child_type_ref;
 
-            for(; index < copy_of->children.size - 1 - offset &&
+            for(; offset < copy_of->children.size &&
-                    result == LIBAB_SUCCESS; index++) {
+                    result == LIBAB_SUCCESS; offset++) {
-                libab_ref_vec_index(&copy_of->children, offset + index, &child_type_ref);
+                libab_ref_vec_index(&copy_of->children, offset, &child_type_ref);
                 result = libab_ref_vec_insert(&new_type->children, &child_type_ref);
                 libab_ref_free(&child_type_ref);
             }
@@ -676,7 +675,7 @@ libab_result _interpreter_partially_apply(struct interpreter_state* state,
     result = _interpreter_copy_function_with_params(state->ab, &value->data, params, scope, &new_function);
     if(result == LIBAB_SUCCESS) {
         libab_ref_free(&new_type);
-        result = _interpreter_copy_type_offset(&value->type, 0, &new_type);
+        result = _interpreter_copy_type_offset(&value->type, params->size, &new_type);
     }
 
     if(result == LIBAB_SUCCESS) {
@@ -1225,7 +1224,7 @@ libab_result _interpreter_run(struct interpreter_state* state, libab_tree* tree,
             _interpreter_create_function_value(state, tree, scope, &function);
 
         if(result == LIBAB_SUCCESS) {
-            result = libab_put_table_value(libab_ref_get(scope),
+            result = libab_overload_function(state->ab, libab_ref_get(scope),
                     tree->string_value, &function);
             if(result != LIBAB_SUCCESS) {
                 libab_ref_free(&function);
@@ -1298,7 +1297,7 @@ libab_result libab_interpreter_run(libab_interpreter* intr, libab_tree* tree,
     return result;
 }
 
-libab_result libab_interpreter_run_function(libab_interpreter* intr,
+libab_result libab_interpreter_call_function(libab_interpreter* intr,
                                             libab_ref* scope,
                                             const char* function,
                                             libab_ref_vec* params,
@@ -1323,6 +1322,21 @@ libab_result libab_interpreter_run_function(libab_interpreter* intr,
     return result;
 }
 
+libab_result libab_interpreter_call_value(libab_interpreter* intr,
+                                         libab_ref* scope,
+                                         libab_ref* function,
+                                         libab_ref_vec* params,
+                                         libab_ref* into) {
+    struct interpreter_state state;
+    libab_result result = LIBAB_SUCCESS;
+
+    _interpreter_init(&state, intr, scope);
+    result = _interpreter_try_call(&state, function, params, into);
+    _interpreter_free(&state);
+    
+    return result;
+}
+
 void libab_interpreter_unit_value(libab_interpreter* intr, libab_ref* into) {
     libab_ref_copy(&intr->value_unit, into);
 }

src/libabacus.c

@@ -102,7 +102,7 @@ libab_result _register_operator(libab* ab, const char* op,
     if ((new_entry = malloc(sizeof(*new_entry)))) {
         new_entry->variant = ENTRY_OP;
         new_operator = &(new_entry->data_u.op);
-        libab_operator_init(new_operator, token_type, precedence, associativity,
+        result = libab_operator_init(new_operator, token_type, precedence, associativity,
                             function);
     } else {
         result = LIBAB_MALLOC;
@@ -161,92 +161,16 @@ libab_result _create_value_function_internal(libab* ab,
     return result;
 }
 
-libab_result _create_value_function_list(libab* ab, libab_ref* into, libab_ref* type) {
-    libab_ref list_ref;
-    libab_result result = libab_create_function_list(ab, &list_ref, type);
-    libab_ref_null(into);
-    if (result == LIBAB_SUCCESS) {
-        libab_ref_free(into);
-        result = libab_create_value_ref(ab, into, &list_ref, type);
-    }
-    libab_ref_free(&list_ref);
-    return result;
-}
-
-libab_result _libab_register_function_existing(libab* ab,
-                                               libab_table_entry* entry,
-                                               libab_ref* function_val) {
-    libab_value* old_value;
-    libab_parsetype* old_type;
-    libab_result result = LIBAB_SUCCESS;
-
-    old_value = libab_ref_get(&entry->data_u.value);
-    old_type = libab_ref_get(&old_value->type);
-
-    if (old_type->data_u.base == &_basetype_function_list) {
-        libab_function_list* list = libab_ref_get(&old_value->data);
-        result = libab_function_list_insert(list, function_val);
-    } else if (old_type->data_u.base == &_basetype_function) {
-        libab_ref new_list;
-        result =
-            _create_value_function_list(ab, &new_list, &ab->type_function_list);
-        if (result == LIBAB_SUCCESS) {
-            libab_function_list* list =
-                libab_ref_get(&((libab_value*)libab_ref_get(&new_list))->data);
-            result = libab_function_list_insert(list, &entry->data_u.value);
-            if (result == LIBAB_SUCCESS) {
-                result = libab_function_list_insert(list, function_val);
-            }
-        }
-        if (result == LIBAB_SUCCESS) {
-            libab_ref_swap(&entry->data_u.value, &new_list);
-        }
-        libab_ref_free(&new_list);
-    } else {
-        libab_ref_swap(&entry->data_u.value, function_val);
-    }
-
-    return result;
-}
-
-libab_result _libab_register_function_new(libab* ab, const char* name,
-                                          libab_ref* function_val) {
-    libab_result result = LIBAB_SUCCESS;
-    libab_table_entry* entry;
-    if ((entry = malloc(sizeof(*entry)))) {
-        entry->variant = ENTRY_VALUE;
-        libab_ref_copy(function_val, &entry->data_u.value);
-        result = libab_table_put(libab_ref_get(&ab->table), name, entry);
-
-        if (result != LIBAB_SUCCESS) {
-            libab_table_entry_free(entry);
-            free(entry);
-        }
-    } else {
-        result = LIBAB_MALLOC;
-    }
-
-    return result;
-}
-
 libab_result libab_register_function(libab* ab, const char* name,
                                      libab_ref* type, libab_function_ptr func) {
-    libab_table_entry* existing_entry;
     libab_ref function_value;
     libab_result result =
         _create_value_function_internal(ab, &function_value, type, func, &ab->table);
 
     if (result == LIBAB_SUCCESS) {
-        existing_entry = libab_table_search_filter(
+        libab_overload_function(ab, libab_ref_get(&ab->table), name, &function_value);
-            libab_ref_get(&ab->table), name, NULL, libab_table_compare_value);
-        if (existing_entry) {
-            result = _libab_register_function_existing(ab, existing_entry,
-                                                       &function_value);
-        } else {
-            result = _libab_register_function_new(ab, name, &function_value);
-        }
-        libab_ref_free(&function_value);
     }
+    libab_ref_free(&function_value);
 
     return result;
 }
@@ -406,7 +330,7 @@ void libab_get_bool_value(libab* ab, int val, libab_ref* into) {
     val ? libab_get_true_value(ab, into) : libab_get_false_value(ab, into);
 }
 
-libab_result _create_tree(libab* ab, const char* string, libab_tree** into) {
+libab_result libab_parse(libab* ab, const char* string, libab_tree** into) {
     libab_result result = LIBAB_SUCCESS;
     ll tokens;
 
@@ -442,7 +366,7 @@ libab_result libab_run(libab* ab, const char* string, libab_ref* value) {
     libab_tree* root;
 
     libab_ref_null(value);
-    result = _create_tree(ab, string, &root);
+    result = libab_parse(ab, string, &root);
 
     if (result == LIBAB_SUCCESS) {
         libab_ref_free(value);
@@ -453,7 +377,7 @@ libab_result libab_run(libab* ab, const char* string, libab_ref* value) {
     return result;
 }
 
-libab_result libab_run_function(libab* ab, const char* function, 
+libab_result libab_call_function(libab* ab, const char* function, 
                                 libab_ref* into,
                                 size_t param_count, ...) {
     libab_ref_vec params;
@@ -465,7 +389,7 @@ libab_result libab_run_function(libab* ab, const char* function,
     result = _handle_va_params(ab, &params, param_count, args);
     if(result == LIBAB_SUCCESS) {
         libab_ref_free(into);
-        result = libab_interpreter_run_function(&ab->intr, &ab->table, function, &params, into);
+        result = libab_interpreter_call_function(&ab->intr, &ab->table, function, &params, into);
 
         libab_ref_vec_free(&params);
     }
@@ -483,7 +407,7 @@ libab_result libab_run_scoped(libab* ab, const char* string, libab_ref* scope, l
     libab_tree* root;
 
     libab_ref_null(into);
-    result = _create_tree(ab, string, &root);
+    result = libab_parse(ab, string, &root);
     if(result == LIBAB_SUCCESS) {
         libab_ref_free(into);
         result = libab_interpreter_run(&ab->intr, root, scope, SCOPE_NONE, into);
@@ -493,7 +417,7 @@ libab_result libab_run_scoped(libab* ab, const char* string, libab_ref* scope, l
     return result;
 }
 
-libab_result libab_run_function_scoped(libab* ab, const char* function, libab_ref* scope, libab_ref* into,
+libab_result libab_call_function_scoped(libab* ab, const char* function, libab_ref* scope, libab_ref* into,
         size_t param_count, ...) {
     libab_ref_vec params;
     libab_result result;
@@ -504,7 +428,7 @@ libab_result libab_run_function_scoped(libab* ab, const char* function, libab_re
     result = _handle_va_params(ab, &params, param_count, args);
     if(result == LIBAB_SUCCESS) {
         libab_ref_free(into);
-        result = libab_interpreter_run_function(&ab->intr, scope, function, &params, into);
+        result = libab_interpreter_call_function(&ab->intr, scope, function, &params, into);
 
         libab_ref_vec_free(&params);
     }

src/parser.c

@@ -525,6 +525,7 @@ libab_result _parse_fun(struct parser_state* state, libab_tree** store_into) {
     libab_result result = LIBAB_SUCCESS;
     int is_parenth, is_comma;
     libab_tree* temp;
+    *store_into = NULL;
     result = _parser_consume_type(state, TOKEN_KW_FUN);
     if (result == LIBAB_SUCCESS) {
         if (_parser_is_type(state, TOKEN_ID)) {
@@ -1056,16 +1057,15 @@ libab_result _parse_expression(struct parser_state* state,
             while (result == LIBAB_SUCCESS && op_stack.tail &&
                    _parser_match_is_op(op_stack.tail->data)) {
                 libab_lexer_match* other_token = op_stack.tail->data;
-                if(other_token->type == TOKEN_OP_INFIX) {
+                if(other_token->type == TOKEN_OP_INFIX || other_token->type == TOKEN_OP_RESERVED) {
-                    _parser_find_operator_infix(state, op_stack.tail->data,
+                    _parser_find_operator_infix(state, other_token, &other_operator);
-                            &other_operator);
                 }
 
                 if (other_token->type == TOKEN_OP_PREFIX ||
                     (operator.associativity == - 1 &&
                      operator.precedence <= other_operator.precedence) ||
                     (operator.associativity == 1 &&
-                     operator.precedence<other_operator.precedence)) {
+                     operator.precedence < other_operator.precedence)) {
                     libab_lexer_match* match = ll_poptail(&op_stack);
                     result = _parser_append_op_node(state, match, &out_stack);
                 } else {

src/parsetype.c

@@ -45,7 +45,7 @@ libab_result libab_parsetype_init_va(libab_parsetype* type,
         result = libab_ref_vec_insert(&type->children, ref);
     }
 
-    if (free_vec) {
+    if (result != LIBAB_SUCCESS && free_vec) {
         libab_ref_vec_free(&type->children);
     }
 

src/refcount_internal.c

@@ -1,16 +0,0 @@
-#include "refcount_internal.h"
-#include <stdlib.h>
-
-void libab_ref_count_changed(libab_ref_count* count) {
-    if (count->strong == 0) {
-        count->strong--;
-        if (count->free_func) {
-            count->free_func(count->data);
-        }
-    }
-    if (count->weak == 0) {
-        if(count->prev) count->prev->next = count->next;
-        if(count->next) count->next->prev = count->prev;
-        free(count);
-    }
-}

src/reserved.c

@@ -4,18 +4,6 @@
 #include "value.h"
 #include "libabacus.h"
 
-libab_result _update_entry(libab_table* table, const char* name, libab_ref* value) {
-    libab_result result = LIBAB_SUCCESS;
-    libab_table_entry* value_entry = libab_table_search_entry_value(table, name);
-    if(value_entry) {
-        libab_ref_free(&value_entry->data_u.value);
-        libab_ref_copy(value, &value_entry->data_u.value);
-    } else {
-        result = libab_put_table_value(table, name, value);
-    }
-    return result;
-}
-
 libab_result _behavior_assign(libab* ab, libab_ref* scope, 
                               libab_tree* left, libab_tree* right,
                               libab_ref* into) {
@@ -24,7 +12,7 @@ libab_result _behavior_assign(libab* ab, libab_ref* scope,
     if(left->variant == TREE_ID) {
         result = libab_run_tree_scoped(ab, right, scope, into);
         if(result == LIBAB_SUCCESS) {
-            result = _update_entry(libab_ref_get(scope), left->string_value, into);
+            result = libab_set_variable(libab_ref_get(scope), left->string_value, into);
         }
 
         if(result != LIBAB_SUCCESS) {
@@ -41,6 +29,61 @@ libab_result _behavior_assign(libab* ab, libab_ref* scope,
     return result;
 }
 
+libab_result _behavior_method(libab* ab, libab_ref* scope,
+                              libab_tree* left, libab_tree* right,
+                              libab_ref* into) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_ref param;
+    libab_ref callee;
+    libab_ref_vec params;
+    int free_params = 0;
+    size_t index = 0;
+
+    libab_ref_null(&callee);
+    if(right->variant == TREE_CALL) {
+        result = libab_ref_vec_init(&params);
+    } else {
+        result = LIBAB_BAD_CALL;
+    }
+
+    if(result == LIBAB_SUCCESS) {
+        free_params = 1;
+        result = libab_run_tree_scoped(ab, left, scope, &param);
+        if(result == LIBAB_SUCCESS) {
+            result = libab_ref_vec_insert(&params, &param);
+        }
+        libab_ref_free(&param);
+    }
+
+    for(; index < right->children.size - 1 && result == LIBAB_SUCCESS; index++) {
+        result = libab_run_tree_scoped(ab, vec_index(&right->children, index),
+                                       scope, &param);
+        if(result == LIBAB_SUCCESS) {
+            result = libab_ref_vec_insert(&params, &param);
+        }
+        libab_ref_free(&param);
+    }
+
+    if(result == LIBAB_SUCCESS) {
+        libab_ref_free(&callee);
+        result = libab_run_tree_scoped(ab, vec_index(&right->children, right->children.size - 1),
+                                      scope, &callee);
+    }
+
+    if(result == LIBAB_SUCCESS) {
+        result = libab_interpreter_call_value(&ab->intr, scope, &callee, &params, into);
+    } else {
+        libab_ref_null(into);
+    }
+
+    if(free_params) {
+        libab_ref_vec_free(&params);
+    }
+    libab_ref_free(&callee);
+
+    return result;
+}
+
 libab_result _expect_boolean(libab* ab, libab_ref* scope,
                           libab_tree* to_run, int* into) {
     libab_result result = LIBAB_SUCCESS;
@@ -103,19 +146,25 @@ libab_result _behavior_lor(libab* ab, libab_ref* scope,
 static const libab_reserved_operator libab_reserved_operators[] = {
     {
         "=", /* Assignment */
-        0,   /* Lowest precedence */
+        -3,  /* Lowest precedence */
         1,   /* Right associative, a = b = 6 should be a = (b = 6) */
         _behavior_assign
     },
+    {
+        ".",
+        -2,
+        -1,
+        _behavior_method
+    },
     {
         "&&", /* Logical and */
-        0,    /* Low precedence */
+        -1,   /* Low precedence */
         -1,   /* Left associative. */
         _behavior_land
     },
     {
         "||", /* Logical or */
-        0,    /* Low precedence */
+        -1,   /* Low precedence */
         -1,   /* Left associative. */
         _behavior_lor
     },

src/table.c

@@ -67,7 +67,7 @@ libab_table_entry* libab_table_search_entry_operator(libab_table* table,
     } else if (type == OPERATOR_INFIX) {
         entry = libab_table_search_filter(table, string, NULL,
                                           libab_table_compare_op_infix);
-    } else if (type == OPERATOR_PREFIX) {
+    } else if (type == OPERATOR_POSTFIX) {
         entry = libab_table_search_filter(table, string, NULL,
                                           libab_table_compare_op_postfix);
     }

src/util.c

@@ -290,9 +290,115 @@ libab_result libab_create_value_raw(libab* ab, libab_ref* into,
     return result;
 }
 
+libab_result _create_value_function_list(libab* ab, libab_ref* into, libab_ref* type) {
+    libab_ref list_ref;
+    libab_result result = libab_create_function_list(ab, &list_ref, type);
+    libab_ref_null(into);
+    if (result == LIBAB_SUCCESS) {
+        libab_ref_free(into);
+        result = libab_create_value_ref(ab, into, &list_ref, type);
+    }
+    libab_ref_free(&list_ref);
+    return result;
+}
+
+
+libab_result _register_function_existing(libab* ab,
+                                         libab_table_entry* entry,
+                                         libab_ref* function_val) {
+    libab_value* old_value;
+    libab_parsetype* old_type;
+    libab_result result = LIBAB_SUCCESS;
+
+    old_value = libab_ref_get(&entry->data_u.value);
+    old_type = libab_ref_get(&old_value->type);
+
+    if (old_type->data_u.base == libab_get_basetype_function_list(ab)) {
+        libab_function_list* list = libab_ref_get(&old_value->data);
+        result = libab_function_list_insert(list, function_val);
+    } else if (old_type->data_u.base == libab_get_basetype_function(ab)) {
+        libab_ref new_list;
+        result =
+            _create_value_function_list(ab, &new_list, &ab->type_function_list);
+        if (result == LIBAB_SUCCESS) {
+            libab_function_list* list =
+                libab_ref_get(&((libab_value*)libab_ref_get(&new_list))->data);
+            result = libab_function_list_insert(list, &entry->data_u.value);
+            if (result == LIBAB_SUCCESS) {
+                result = libab_function_list_insert(list, function_val);
+            }
+        }
+        if (result == LIBAB_SUCCESS) {
+            libab_ref_swap(&entry->data_u.value, &new_list);
+        }
+        libab_ref_free(&new_list);
+    } else {
+        libab_ref_swap(&entry->data_u.value, function_val);
+    }
+
+    return result;
+}
+
+libab_result _register_function_new(libab* ab, const char* name,
+                                          libab_ref* function_val) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_table_entry* entry;
+    if ((entry = malloc(sizeof(*entry)))) {
+        entry->variant = ENTRY_VALUE;
+        libab_ref_copy(function_val, &entry->data_u.value);
+        result = libab_table_put(libab_ref_get(&ab->table), name, entry);
+
+        if (result != LIBAB_SUCCESS) {
+            libab_table_entry_free(entry);
+            free(entry);
+        }
+    } else {
+        result = LIBAB_MALLOC;
+    }
+
+    return result;
+}
+
+
+libab_result libab_overload_function(libab* ab,
+                                     libab_table* table,
+                                     const char* name,
+                                     libab_ref* function) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_table_entry* existing_entry = libab_table_search_filter(
+            table, name, NULL, libab_table_compare_value);
+
+    if (existing_entry) {
+        result = _register_function_existing(ab, existing_entry,
+                function);
+    } else {
+        result = _register_function_new(ab, name, function);
+    }
+
+    return result;
+}
+
+libab_result libab_set_variable(libab_table* table,
+                                const char* name,
+                                libab_ref* value) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_table_entry* value_entry = libab_table_search_entry_value(table, name);
+    if(value_entry) {
+        libab_ref_free(&value_entry->data_u.value);
+        libab_ref_copy(value, &value_entry->data_u.value);
+    } else {
+        result = libab_put_table_value(table, name, value);
+    }
+    return result;
+}
+
 void _gc_visit_function_children(void* function, libab_visitor_function_ptr visitor, void* data) {
+    size_t index = 0;
     libab_function* func = function;
     libab_gc_visit(&func->scope, visitor, data);
+    for(; index < func->params.size; index++) {
+        libab_gc_visit(&func->params.data[index], visitor, data);
+    }
 }
 
 libab_result libab_create_function_internal(libab* ab, libab_ref* into,
@@ -385,6 +491,15 @@ libab_result libab_create_function_behavior(libab* ab, libab_ref* into,
     return result;
 }
 
+
+void _gc_visit_function_list_children(void* list, libab_visitor_function_ptr visitor, void* data) {
+    size_t index = 0;
+    libab_function_list* func_list = list;
+    for(; index < func_list->functions.size; index++) {
+        libab_gc_visit(&func_list->functions.data[index], visitor, data);
+    }
+}
+
 libab_result libab_create_function_list(libab* ab, libab_ref* into, libab_ref* type) {
     libab_function_list* list;
     libab_result result = LIBAB_SUCCESS;
@@ -408,7 +523,7 @@ libab_result libab_create_function_list(libab* ab, libab_ref* into, libab_ref* t
         libab_ref_null(into);
         free(list);
     } else {
-        libab_gc_add(into, _gc_visit_function_children, &ab->containers);
+        libab_gc_add(into, _gc_visit_function_list_children, &ab->containers);
     }
 
     return result;
@@ -471,9 +586,29 @@ void libab_sanitize(char* to, const char* from, size_t buffer_size) {
     while (*from && index < (buffer_size - 2)) {
         if (*from == '+' || *from == '*' || *from == '\\' ||
                 *from == '|' || *from == '[' || *from == ']' || *from == '(' ||
-                *from == ')')
+                *from == ')' || *from == '.')
             to[index++] = '\\';
         to[index++] = *(from++);
     }
     to[index] = '\0';
 }
+
+libab_result libab_create_instance(libab** into, 
+                                   void* (*parse_function)(const char*),
+                                   void (*free_function)(void*)) {
+    libab_result result = LIBAB_SUCCESS;
+    if((*into = malloc(sizeof(**into)))) {
+        result = libab_init(*into, parse_function, free_function);
+        if(result != LIBAB_SUCCESS) {
+            free(*into);
+            *into = NULL;
+        }
+    } else {
+        result = LIBAB_MALLOC;
+    }
+    return result;
+}
+void libab_destroy_instance(libab* into) {
+    libab_free(into);
+    free(into);
+}