Implement code generation for the new syntax

Author: chengluyu

shared/src/main/scala/mlscript/JSBackend.scala

@@ -240,7 +240,13 @@ class JSBackend(allowUnresolvedSymbols: Boolean) {
         case N => throw CodeGenError(s"if expression has not been not desugared")
         case S(term) => translateTerm(term)
       }
-    case _: Bind | _: Test | If(_, _) | New(_, _) | TyApp(_, _) | _: Splc =>
+    case New(N, TypingUnit(Nil)) => JSRecord(Nil)
+    case New(S(TypeName(className) -> Tup(args)), TypingUnit(Nil)) =>
+      val callee = translateVar(className, true)
+      callee(args.map { case (_, Fld(_, _, arg)) => translateTerm(arg) }: _*)
+    case New(_, TypingUnit(_)) =>
+      throw CodeGenError("custom class body is not supported yet")
+    case _: Bind | _: Test | If(_, _) | TyApp(_, _) | _: Splc =>
       throw CodeGenError(s"cannot generate code for term ${inspect(term)}")
   }
 

shared/src/test/diff/codegen/Terms.mls

@@ -344,11 +344,17 @@ case A { a = 0 } of
 
 // With
 {} with {}
-:js
 rcd1 = { x = "a"; y = "b" }
 rcd2 = rcd1 with { x = 1; z = 2 }
 (rcd1.x, rcd1.y, rcd2.x, rcd2.y, rcd2.z)
-//│ /!\ Parse error: Expected end-of-input:1:12, found ":js;rcd1 =" at l.347:1: :js
+//│ res: anything
+//│    = {}
+//│ rcd1: {x: "a", y: "b"}
+//│     = { x: 'a', y: 'b' }
+//│ rcd2: {x: 1, y: "b", z: 2}
+//│     = { x: 1, y: 'b', z: 2 }
+//│ res: ("a", "b", 1, "b", 2,)
+//│    = [ 'a', 'b', 1, 'b', 2 ]
 
 class M: {mut x : int}
 //│ Defined class M

shared/src/test/diff/nu/New.mls

@@ -10,11 +10,9 @@ let f = Foo(1)
 //│ f: Foo & {x: 1}
 //│  = Foo { x: 1 }
 
-:ge
 let f = new Foo(1)
 //│ f: Foo & {x: 1}
-//│ Code generation encountered an error:
-//│   cannot generate code for term New(Some((TypeName(Foo),1,)), TypingUnit(List()))
+//│  = Foo { x: 1 }
 
 if f is Foo(a) then a else 0
 //│ res: 1
@@ -38,3 +36,11 @@ test(f)
 //│ res: 1
 //│    = 1
 
+class Point(x, y)
+//│ Defined class Point
+//│ Point: ('x, 'y,) -> (Point with {x: 'x, y: 'y})
+//│      = [Function: Point1]
+
+let origin = new Point(0, 0)
+//│ origin: Point & {x: 0, y: 0}
+//│       = Point { x: 0, y: 0 }