expose functions to lisp interface, add primitives with macros

1 files changed, 18 insertions, 1 deletions

diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index 4676a3e..adacc1c 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -11,7 +11,7 @@ pub enum LispExpr {
     StringLit(String),
     BoolLit(bool),
     Ident(String),
-    PrimitiveFunc(fn(&[LispExpr], Option<&mut AppState>) -> Result<LispExpr, LispError>),
+    PrimitiveFunc(PrimitiveFunc),
     Function(LispFunction),
 
     // none of these depths should be zero
@@ -21,6 +21,23 @@ pub enum LispExpr {
     Quote(Box<LispExpr>, u32),
 }
 
+#[derive(Clone)]
+pub struct PrimitiveFunc {
+    pub arity: Option<usize>,
+    pub closure: fn(&[LispExpr], &mut AppState) -> Result<LispExpr, LispError>,
+}
+
+impl PrimitiveFunc {
+    pub fn call(&self, args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
+        if let Some(arity) = self.arity {
+            if args.len() < arity {
+                return Err(LispError::EvalError);
+            }
+        }
+        (self.closure)(args, app)
+    }
+}
+
 impl LispExpr {
     pub fn comma(self, n: u32) -> LispExpr {
         match self {