# HG changeset patch
# User Simon Heath <icefox@dreamquest.io>
# Date 1670276483 18000
#      Mon Dec 05 16:41:23 2022 -0500
# Node ID efd98a53c3fe474ad24a5d424c80af3e3bc7020a
# Parent  964fb997a0f31b0b753074050c92faf701f74db2
BEHOLD MY POWER MUAHAHAAHAHHAHAHAHAAAAAA

diff --git a/fml/src/ast.rs b/fml/src/ast.rs
--- a/fml/src/ast.rs
+++ b/fml/src/ast.rs
@@ -78,7 +78,7 @@
     },
     Let {
         varname: String,
-        typename: Type,
+        typename: Option<Type>,
         init: ExprNode,
     },
     Lambda {
diff --git a/fml/src/parser.rs b/fml/src/parser.rs
--- a/fml/src/parser.rs
+++ b/fml/src/parser.rs
@@ -626,8 +626,11 @@
     fn parse_let(&mut self) -> ast::ExprNode {
         self.expect(T::Let);
         let varname = self.expect_ident();
-        self.expect(T::Colon);
-        let typename = self.parse_type();
+        let typename = if self.peek_expect(T::Colon.discr()) {
+            Some(self.parse_type())
+        } else {
+            None
+        };
         self.expect(T::Equals);
         let init = self
             .parse_expr(0)
diff --git a/fml/src/typeck.rs b/fml/src/typeck.rs
--- a/fml/src/typeck.rs
+++ b/fml/src/typeck.rs
@@ -214,6 +214,8 @@
                     // rather than "unknown name".  Guess it works for now though.
                     //
                     // TODO: The scoping here is still bananas, figure it out
+                    // I think we need to get the generic names from the function call
+                    // and figure 'em out, rather than just casually adding 'em in here
                     let tid = self.insert(TypeInfo::Unknown);
                     named_types.insert(s.clone(), tid);
                     TypeInfo::Ref(tid)
@@ -405,7 +407,11 @@
         } => {
             typecheck_expr(tck, symtbl, init)?;
             let init_expr_type = tck.get_expr_type(init);
-            let var_type = tck.insert_known(typename);
+            let var_type = if let Some(t) = typename {
+                tck.insert_known(t)
+            } else {
+                tck.insert(TypeInfo::Unknown)
+            };
             tck.unify(symtbl, init_expr_type, var_type)?;
 
             // TODO: Make this expr return unit instead of the
@@ -521,8 +527,6 @@
             tck.unify(symtbl, tid, body_type)?;
             println!("Done unifying type ctor");
             // The type the expression returns
-            // TODO: Generic params for type constructors
-            //let constructed_type = tck.insert_known(&Type::Named(name.clone(), vec![]));
             let constructed_type =
                 tck.insert_known(&Type::Named(name.clone(), type_params.clone()));
             tck.set_expr_type(expr, constructed_type);
diff --git a/fml/tests/main.rs b/fml/tests/main.rs
--- a/fml/tests/main.rs
+++ b/fml/tests/main.rs
@@ -138,3 +138,9 @@
     let src = include_str!("test_struct5.gt");
     let _output = fml::compile("test_struct5.gt", src);
 }
+
+#[test]
+fn test_let1() {
+    let src = include_str!("test_let1.gt");
+    let _output = fml::compile("test_let1.gt", src);
+}
diff --git a/fml/tests/test_let1.gt b/fml/tests/test_let1.gt
new file mode 100644
--- /dev/null
+++ b/fml/tests/test_let1.gt
@@ -0,0 +1,25 @@
+
+type Foo(@Thing) = struct
+    a: @Thing,
+    b: Bool
+end
+
+fn id(x: @T): @T =
+    x
+end
+
+
+fn main(): I32 =
+    let f1 = id($Foo(I32) {
+        .a = 3,
+        .b = false
+    })
+
+    let f2 = id($Foo(Bool) {
+        .a = true,
+        .b = false
+    })
+
+    let f3 = f1
+    3
+end