Use type aliases when pretty printing types

src/pretty_print_types.rs

@@ -28,22 +28,7 @@ fn write_flat_type(flat_type: FlatType, subs: &mut Subs, buf: &mut String, use_p
 
     match flat_type {
         Apply(module_name, type_name, args) => {
-            let write_parens = use_parens && !args.is_empty();
+            write_apply(module_name, type_name, args, subs, buf, use_parens)
-
-            if write_parens {
-                buf.push_str("(");
-            }
-
-            buf.push_str(&format!("{}.{}", module_name, type_name));
-
-            for arg in args {
-                buf.push_str(" ");
-                write_content(subs.get(arg).content, subs, buf, true);
-            }
-
-            if write_parens {
-                buf.push_str(")");
-            }
         },
         EmptyRecord => buf.push_str(EMPTY_RECORD),
         Func(args, ret) => {
@@ -58,6 +43,58 @@ fn write_flat_type(flat_type: FlatType, subs: &mut Subs, buf: &mut String, use_p
     }
 }
 
+fn write_apply(module_name: String, type_name: String, args: Vec<Variable>, subs: &mut Subs, buf: &mut String, use_parens: bool) {
+    let write_parens = use_parens && !args.is_empty();
+
+    // Hardcoded type aliases
+    if module_name == "Num" && type_name == "Num" {
+        let arg = args.into_iter().next().unwrap_or_else(|| {
+            panic!("Num did not have any type parameters somehow.")
+        });
+        let arg_content = subs.get(arg).content;
+        let mut arg_param = String::new();
+
+        write_content(arg_content, subs, &mut arg_param, true);
+
+        if arg_param == "Int.Integer" {
+            buf.push_str("Int");
+        } else if arg_param == "Float.FloatingPoint" {
+            buf.push_str("Float");
+        } else {
+            if write_parens { buf.push_str("("); }
+
+            buf.push_str("Num ");
+            buf.push_str(&arg_param);
+
+            if write_parens { buf.push_str(")"); }
+        }
+    } else if module_name == "List" && type_name == "List" {
+        if write_parens { buf.push_str("("); }
+
+        buf.push_str("List ");
+
+        let arg = args.into_iter().next().unwrap_or_else(|| {
+            panic!("List did not have any type parameters somehow.")
+        });
+        let arg_content = subs.get(arg).content;
+
+        write_content(arg_content, subs, buf, true);
+
+        if write_parens { buf.push_str(")"); }
+    } else {
+        if write_parens { buf.push_str("("); }
+
+        buf.push_str(&format!("{}.{}", module_name, type_name));
+
+        for arg in args {
+            buf.push_str(" ");
+            write_content(subs.get(arg).content, subs, buf, true);
+        }
+
+        if write_parens { buf.push_str(")"); }
+    }
+}
+
 fn write_fn(args: Vec<Variable>, ret: Variable, subs: &mut Subs, buf: &mut String, use_parens: bool) {
     let mut needs_comma = false;