1 files changed, 59 insertions, 7 deletions
diff --git a/src/builtins.rs b/src/builtins.rs
index dbc17eb..b8b789f 100644
--- a/src/builtins.rs
+++ b/src/builtins.rs
@@ -4,6 +4,8 @@ use std::rc::Rc;
 
 pub const B_INTEGER_EQ0: &str = "int.eq0?";
 pub const B_INTEGER_INCREMENT: &str = "int.increment";
+pub const B_INTEGER_ADD: &str = "int.add";
+pub const B_INTEGER_ADD_1: &str = "##int.add_1";
 
 pub fn make_boolean_true_function() -> Term {
     let x = advance_v();
@@ -27,13 +29,18 @@ pub fn try_ast_symbol_to_builtin_term(symbol: &ast::Symbol) -> Option<Term> {
         "true" => Some(make_boolean_true_function()),
         "false" => Some(make_boolean_false_function()),
         "id" => Some(make_identity_function()),
-        B_INTEGER_EQ0 => Some(Term::Builtin(String::from(B_INTEGER_EQ0))),
-        B_INTEGER_INCREMENT => Some(Term::Builtin(String::from(B_INTEGER_INCREMENT))),
+        B_INTEGER_EQ0 => Some(Term::Builtin(String::from(B_INTEGER_EQ0), vec![])),
+        B_INTEGER_INCREMENT => Some(Term::Builtin(String::from(B_INTEGER_INCREMENT), vec![])),
+        B_INTEGER_ADD => Some(Term::Builtin(String::from(B_INTEGER_ADD), vec![])),
         _ => None,
     }
 }
 
-pub fn evaluate_builtin(symbol: &String, rhs: Rc<Term>) -> Result<(Rc<Term>, usize), String> {
+pub fn evaluate_builtin(
+    symbol: &String,
+    bound_arguments: &Vec<Value>,
+    rhs: Rc<Term>,
+) -> Result<(Rc<Term>, usize), String> {
     let result_term = match symbol.as_str() {
         B_INTEGER_EQ0 => match &*rhs {
             Term::Primitive(primitive) => match primitive {
@@ -46,24 +53,69 @@ pub fn evaluate_builtin(symbol: &String, rhs: Rc<Term>) -> Result<(Rc<Term>, usi
                 }
                 other => {
                     return Err(format!(
-                        "[runtime] cannot apply builtin {} to argument type {}",
+                        "[runtime] cannot apply builtin {} to argument {}",
                         symbol, other
                     ))
                 }
             },
-            _ => return Ok((Rc::new(Term::Builtin(symbol.clone())), 0)),
+            _ => return Ok((Rc::new(Term::Builtin(symbol.clone(), vec![])), 0)),
         },
         B_INTEGER_INCREMENT => match &*rhs {
             Term::Primitive(primitive) => match primitive {
                 Value::Integer(value) => Term::Primitive(Value::Integer(value + 1)),
                 other => {
                     return Err(format!(
-                        "[runtime] cannot apply builtin {} to argument type {}",
+                        "[runtime] cannot apply builtin {} to argument {}",
                         symbol, other
                     ))
                 }
             },
-            _ => return Ok((Rc::new(Term::Builtin(symbol.clone())), 0)),
+            _ => return Ok((Rc::new(Term::Builtin(symbol.clone(), vec![])), 0)),
+        },
+        B_INTEGER_ADD => match &*rhs {
+            Term::Primitive(primitive) => match primitive {
+                Value::Integer(_) => {
+                    Term::Builtin(String::from(B_INTEGER_ADD_1), vec![primitive.clone()])
+                }
+                other => {
+                    return Err(format!(
+                        "[runtime] cannot apply builtin {} to argument {}",
+                        symbol, other
+                    ))
+                }
+            },
+            _ => return Ok((Rc::new(Term::Builtin(symbol.clone(), vec![])), 0)),
+        },
+        B_INTEGER_ADD_1 => match &*rhs {
+            Term::Primitive(primitive) => match primitive {
+                Value::Integer(value) => {
+                    assert_eq!(bound_arguments.len(), 1);
+                    let summand = &bound_arguments[0];
+                    match summand {
+                        Value::Integer(summand_value) => {
+                            Term::Primitive(Value::Integer(summand_value + value))
+                        }
+                        other => {
+                            return Err(format!(
+                                "[runtime] cannot apply builtin {} to argument {}",
+                                symbol, other
+                            ))
+                        }
+                    }
+                }
+                other => {
+                    return Err(format!(
+                        "[runtime] cannot apply builtin {} to argument {}",
+                        symbol, other
+                    ))
+                }
+            },
+            _ => {
+                return Ok((
+                    Rc::new(Term::Builtin(symbol.clone(), bound_arguments.clone())),
+                    0,
+                ))
+            }
         },
         _ => return Err(format!("[runtime] invalid builtin evaluated: {}", symbol)),
     };