diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5aff539..9718608 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,6 +10,7 @@ add_compile_options(-pedantic -Wall)
 
 add_library(abacus STATIC src/lexer.c src/util.c src/table.c src/parser.c src/libabacus.c src/tree.c src/debug.c src/parsetype.c src/reserved.c src/trie.c src/refcount.c src/ref_vec.c src/ref_trie.c src/basetype.c src/value.c src/custom.c src/interpreter.c src/function_list.c)
 add_executable(libabacus src/main.c)
+add_executable(interactive src/interactive.c)
 add_subdirectory(external/liblex)
 
 set_property(TARGET abacus PROPERTY C_STANDARD 90)
@@ -19,3 +20,4 @@ target_include_directories(libabacus PUBLIC include)
 
 target_link_libraries(abacus lex)
 target_link_libraries(libabacus abacus)
+target_link_libraries(interactive abacus)
diff --git a/src/interactive.c b/src/interactive.c
new file mode 100644
index 0000000..10cfcd5
--- /dev/null
+++ b/src/interactive.c
@@ -0,0 +1,87 @@
+#include "libabacus.h"
+#include <stdio.h>
+
+#define TRY(expression) if(result == LIBAB_SUCCESS) result = expression;
+#define INTERACTIONS 5
+
+void* impl_parse(const char* string) {
+    double* data = malloc(sizeof(*data));
+    if(data) {
+        *data = strtod(string, NULL);
+    }
+    return data;
+}
+
+void impl_free(void* data) {
+    free(data);
+}
+
+libab_result function_atan(libab_ref_vec* params, libab_ref* into) {
+    printf("atan called\n");
+    libab_ref_null(into);
+    return LIBAB_SUCCESS;
+}
+
+libab_result function_atan2(libab_ref_vec* params, libab_ref* into) {
+    printf("atan2 called\n");
+    libab_ref_null(into);
+    return LIBAB_SUCCESS;
+}
+
+libab_result function_operator(libab_ref_vec* params, libab_ref* into) {
+    printf("operator called\n");
+    libab_ref_null(into);
+    return LIBAB_SUCCESS;
+}
+
+libab_result register_functions(libab* ab) {
+    libab_result result = LIBAB_SUCCESS;
+    libab_ref trig_type;
+    libab_ref atan2_type;
+    libab_ref difficult_type;
+
+    result = libab_create_type(ab, &trig_type, "(num)->num");
+    TRY(libab_create_type(ab, &atan2_type, "(num, num)->num"));
+    TRY(libab_create_type(ab, &difficult_type, "((num)->num)->num"));
+
+    TRY(libab_register_function(ab, "atan", &trig_type, function_atan));
+    TRY(libab_register_function(ab, "atan2", &atan2_type, function_atan2));
+    TRY(libab_register_operator_infix(ab, "+", 0, -1, &atan2_type, function_operator));
+    TRY(libab_register_operator_infix(ab, "-", 0, -1, &atan2_type, function_operator));
+    TRY(libab_register_operator_infix(ab, "*", 1, -1, &atan2_type, function_operator));
+    TRY(libab_register_operator_infix(ab, "/", 1, -1, &atan2_type, function_operator));
+
+    libab_ref_free(&trig_type);
+    libab_ref_free(&atan2_type);
+    libab_ref_free(&difficult_type);
+
+    return result;
+}
+
+int main() {
+    char input_buffer[2048];
+    int interaction_count = INTERACTIONS;
+    libab_ref eval_into;
+    libab_result result;
+    libab_result eval_result;
+    libab ab;
+
+    if(libab_init(&ab, impl_parse, impl_free) != LIBAB_SUCCESS) {
+        fprintf(stderr, "Failed to initialize libab.\n");
+        exit(1);
+    }
+
+    result = register_functions(&ab);
+    while(interaction_count-- && result == LIBAB_SUCCESS) {
+        printf("(%d) > ", INTERACTIONS - interaction_count);
+        fgets(input_buffer, 2048, stdin);
+        eval_result = libab_run(&ab, input_buffer, &eval_into);
+
+        if(eval_result != LIBAB_SUCCESS) {
+            printf("Invalid input.\n");
+        }
+        libab_ref_free(&eval_into);
+    }
+
+    libab_free(&ab);
+}