feat: expand term try, for, unless, and return

src/Lean/Elab/Do.lean

@@ -1514,6 +1514,24 @@ end Do
 
 builtin_initialize registerTraceClass `Elab.do
 
+private def toDoElem (newKind : SyntaxNodeKind) : Macro := fun stx => do
+  let stx := stx.setKind newKind
+  let stxNew ← `(do $stx:doElem)
+  return stxNew.copyInfo stx
+
+@[builtinMacro Lean.Parser.Term.termFor]
+def expandTermFor : Macro := toDoElem `Lean.Parser.Term.doFor
+
+@[builtinMacro Lean.Parser.Term.termTry]
+def expandTermTry : Macro := toDoElem `Lean.Parser.Term.doTry
+
+@[builtinMacro Lean.Parser.Term.termUnless]
+def expandTermUnless : Macro := toDoElem `Lean.Parser.Term.doUnless
+
+@[builtinMacro Lean.Parser.Term.termReturn]
+def expandTermReturn : Macro := toDoElem `Lean.Parser.Term.doReturn
+
+
 end Term
 end Elab
 end Lean

tests/lean/doElemAsTermNotation.lean

@@ -0,0 +1,27 @@
+def f1 (x : Nat) : IO Unit :=
+  unless x > 10 do
+    IO.println s!"x: {x}"
+
+#eval f1 0
+#eval f1 100
+
+def f2 (x : Nat) (ref : IO.Ref Nat) : IO Nat :=
+  return x + (←ref.get)
+
+#eval id (α := IO Nat) do f2 5 (← IO.mkRef 10)
+
+def f3 (x : Nat) : IO Nat :=
+  try
+    IO.println x
+    throw $ IO.userError "failed"
+  catch
+    | IO.Error.userError msg => IO.println s!"at catch: {msg}"; pure 0
+    | ex => throw ex
+
+#eval f3 5
+
+def f4 (xs : List Nat) : IO Unit :=
+  for x in xs do
+    IO.println x
+
+#eval f4 [1,2,3]