From b695ad75fa299bfc068d78a3369930cdb0043af5 Mon Sep 17 00:00:00 2001
From: Peter <peterhsaxton@gmail.com>
Date: Mon, 10 Oct 2022 20:18:58 +0200
Subject: [PATCH] try a tree shaking algorithm

---
 eyg/src/eyg/entry.gleam          |  20 +++--
 eyg/test/eyg/analysis_test.gleam | 130 +++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+), 8 deletions(-)
 create mode 100644 eyg/test/eyg/analysis_test.gleam

diff --git a/eyg/src/eyg/entry.gleam b/eyg/src/eyg/entry.gleam
index eeb268a9a..776974bbe 100644
--- a/eyg/src/eyg/entry.gleam
+++ b/eyg/src/eyg/entry.gleam
@@ -15,7 +15,6 @@ import eyg/typer
 import eyg/typer/monotype as t
 import eyg/editor/editor
 
-
 fn update(page, interrupt, display, on_click) {
   io.debug(page)
   display(page)
@@ -25,9 +24,14 @@ fn b(args) {
   Ok(args)
 }
 
-fn tree() { 
-  r.Function(p.Variable("x"), e.tuple_([e.variable("x"),e.variable("x")]), map.new(), None)
- }
+fn tree() {
+  r.Function(
+    p.Variable("x"),
+    e.tuple_([e.variable("x"), e.variable("x")]),
+    map.new(),
+    None,
+  )
+}
 
 // uses default builtin that need moving out of effectful
 // has an entry point key should eventually be a hash
@@ -44,12 +48,12 @@ pub fn interpret_client(source, key, display, on_click) {
   let #(xtyped, typer) =
     typer.expand_providers(typed, typer, [])
     // Running the interpreter kills the client
-      // assert Ok(term) = effectful.eval(editor.untype(xtyped))
-      // io.debug(term)
+    // assert Ok(term) = effectful.eval(editor.untype(xtyped))
+    // io.debug(term)
     |> io.debug
   io.debug("expanded")
-    effectful.eval_call(tree(), r.Binary("nothing exciting"), effectful.real_log)
-    |> io.debug
+  effectful.eval_call(tree(), r.Binary("nothing exciting"), effectful.real_log)
+  |> io.debug
   // //   TODO make an AST the requires rendering
   //   term
 }
diff --git a/eyg/test/eyg/analysis_test.gleam b/eyg/test/eyg/analysis_test.gleam
new file mode 100644
index 000000000..456f0ebed
--- /dev/null
+++ b/eyg/test/eyg/analysis_test.gleam
@@ -0,0 +1,130 @@
+import gleam/io
+import gleam/option.{Some}
+import gleam/list
+import gleam/string
+import eyg/ast/expression as e
+import eyg/ast/pattern as p
+import eyg/typer/monotype as t
+import eyg/analysis
+import eyg/typer
+
+fn variables_needed(source) {
+  do_variables_needed(source)
+  |> list.unique
+  |> list.sort(string.compare)
+}
+
+fn do_variables_needed(tree) {
+  let #(_, exp) = tree
+  case exp {
+    e.Binary(_) | e.Hole -> []
+    e.Variable(label) -> [label]
+    e.Tuple(elems) ->
+      list.fold(
+        elems,
+        [],
+        fn(acc, e) { list.append(acc, do_variables_needed(e)) },
+      )
+    e.Record(fields) ->
+      list.fold(
+        fields,
+        [],
+        fn(acc, f) {
+          let #(_, e) = f
+          list.append(acc, do_variables_needed(e))
+        },
+      )
+    e.Access(e, _) | e.Tagged(_, e) -> do_variables_needed(e)
+    e.Call(f, arg) ->
+      list.append(do_variables_needed(f), do_variables_needed(arg))
+    e.Let(_p, value, then) ->
+      list.append(do_variables_needed(value), do_variables_needed(then))
+    //   TODO pattern
+    e.Function(_p, body) -> do_variables_needed(body)
+    e.Case(value, branches) ->
+      list.fold(
+        branches,
+        do_variables_needed(value),
+        fn(acc, b) {
+          // TODO remove pattern
+          let #(_, _, then) = b
+          list.append(acc, do_variables_needed(then))
+        },
+      )
+    //   TODO these shouldn't add anything new or we will change them to be eval'd functions
+    e.Provider(_, _, _) -> []
+  }
+  // _ -> todo
+}
+
+fn by_type(tree, scope) {
+  assert Ok(typer) = do_type(tree, scope, typer.init())
+  t.resolve(scope, typer.substitutions)
+}
+
+fn do_type(tree, scope, state) -> Result(typer.Typer, _) {
+  let #(_, exp) = tree
+  case exp {
+    e.Variable(label) -> {
+      let #(row, state) = typer.next_unbound(state)
+      let #(type_, state) = typer.next_unbound(state)
+      typer.unify(
+        t.Record([#(label, t.Unbound(type_))], Some(row)),
+        scope,
+        state,
+      )
+    }
+    e.Let(_, value, then) -> do_type(value, scope, state)
+    e.Access(term, key) ->
+      // This is on the type of the term does nothing to scope. I think need to run through checking the typer
+      todo
+    _ -> {
+      io.debug(exp)
+      todo
+    }
+  }
+}
+
+pub fn slim_records_test() -> Nil {
+  //   e.let_(p.Record([]), e.record([]), e.hole())
+
+  let source = e.variable("x")
+  assert _ =
+    by_type(source, t.Unbound(-1))
+    |> io.debug
+
+  let source =
+    e.let_(
+      p.Variable(""),
+      e.access(e.variable("x"), "foo"),
+      e.let_(p.Variable(""), e.access(e.variable("x"), "foo"), e.hole()),
+    )
+
+  assert _ =
+    by_type(source, t.Unbound(-1))
+    |> io.debug
+  todo("slim")
+}
+
+pub fn capturing_all_type_variables_test() {
+  // If there is a function from string -> string could be a -> b a -> string b -> string
+  // how do providers work over this
+  let source = e.variable("x")
+  assert ["x"] = variables_needed(source)
+
+  let source = e.binary("hello")
+  assert [] = variables_needed(source)
+
+  let source = e.call(e.variable("x"), e.variable("y"))
+  assert ["x", "y"] = variables_needed(source)
+
+  let source = e.tuple_([e.variable("x"), e.variable("y")])
+  assert ["x", "y"] = variables_needed(source)
+
+  let source = e.access(e.variable("x"), "y")
+  assert ["x"] = variables_needed(source)
+
+  let source = e.tagged("Y", e.variable("x"))
+  assert ["x"] = variables_needed(source)
+  //   todo("test")
+}