actually compiles and does stuff now

src/ir/upper/def.rs

@@ -0,0 +1,39 @@
+use super::{FileSpan, Type};
+use std::fmt::Debug;
+
+#[derive(Clone)]
+pub struct FnDef {
+    pub name: String,
+    pub args: Vec<VarDef>,
+    pub ret: Type,
+    pub origin: Origin,
+}
+
+#[derive(Clone)]
+pub struct TypeDef {
+    pub name: String,
+    pub args: usize,
+    pub origin: Origin,
+}
+
+#[derive(Clone)]
+pub struct VarDef {
+    pub name: String,
+    pub ty: Type,
+    pub origin: Origin,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Origin {
+    Builtin,
+    File(FileSpan),
+}
+
+impl FnDef {
+    pub fn ty(&self) -> Type {
+        Type::Fn {
+            args: self.args.iter().map(|a| a.ty.clone()).collect(),
+            ret: Box::new(self.ret.clone()),
+        }
+    }
+}