Fix problems with selections and related features

hkmc2/shared/src/main/scala/hkmc2/codegen/Lowering.scala

@@ -82,13 +82,23 @@ class Lowering(using TL, Raise, Elaborator.State):
             TODO("Other argument forms")
           case spd: Spd => true -> spd.term
         val l = new TempSymbol(S(t))
-        subTerm(f): fr =>
+        def conclude(fr: Path) =
           def rec(as: Ls[Bool -> st], asr: Ls[Arg]): Block = as match
             case Nil => k(Call(fr, asr.reverse)(isMlsFun))
             case (spd, a) :: as =>
               subTerm(a): ar =>
                 rec(as, Arg(spd, ar) :: asr)
           rec(as, Nil)
+        f match
+        // * Due to whacky JS semantics, we need to make sure that selections leading to a call
+        // * are preserved in the call and not moved to a temporary variable.
+        case sel @ Sel(prefix, nme) =>
+          subTerm(prefix): p =>
+            conclude(Select(p, nme)(sel.sym))
+        case sel @ SelProj(prefix, _, nme) =>
+          subTerm(prefix): p =>
+            conclude(Select(p, nme)(sel.sym))
+        case _ => subTerm(f)(conclude)
       case _ =>
         TODO("Other argument list forms")
     case st.Blk(Nil, res) => term(res)(k)
@@ -325,8 +335,8 @@ class Lowering(using TL, Raise, Elaborator.State):
       End("error")
 
     // * BbML-specific cases: t.Cls#field and mutable operations
-    case SelProj(prefix, _, proj) =>
-      setupSelection(prefix, proj, N)(k)
+    case sp @ SelProj(prefix, _, proj) =>
+      setupSelection(prefix, proj, sp.sym)(k)
     case Region(reg, body) =>
       Assign(reg, Instantiate(Select(Value.Ref(State.globalThisSymbol), Tree.Ident("Region"))(N), Nil), term(body)(k))
     case RegRef(reg, value) =>

hkmc2/shared/src/main/scala/hkmc2/semantics/Elaborator.scala

@@ -307,12 +307,19 @@ extends Importer:
       Term.CompType(term(lhs), term(rhs), false)
     case App(Ident(":="), Tree.Tup(lhs :: rhs :: Nil)) =>
       Term.SetRef(term(lhs), term(rhs))
-    case App(Ident("#"), Tree.Tup(SynthSel(pre, idn: Ident) :: (idp: Ident) :: Nil)) =>
-      Term.SelProj(term(pre), term(idn), idp)
-    case App(Ident("#"), Tree.Tup(SynthSel(pre, Ident(name)) :: App(Ident(proj), args) :: Nil)) =>
-      term(App(App(Ident("#"), Tree.Tup(SynthSel(pre, Ident(name)) :: Ident(proj) :: Nil)), args))
     case App(Ident("#"), Tree.Tup(Sel(pre, idn: Ident) :: (idp: Ident) :: Nil)) =>
-      Term.SelProj(term(pre), term(idn), idp)
+      val c = cls(idn, inAppPrefix = false)
+      val f = c.symbol.flatMap(_.asCls) match
+        case S(cls: ClassSymbol) =>
+          cls.tree.allSymbols.get(idp.name) match
+          case S(fld: FieldSymbol) => S(fld)
+          case _ =>
+            raise(ErrorReport(msg"Class '${cls.nme}' does not contain member '${idp.name}'." -> idp.toLoc :: Nil))
+            N
+        case _ =>
+          raise(ErrorReport(msg"Identifier `${idn.name}` does not name a known class symbol." -> idn.toLoc :: Nil))
+          N
+      Term.SelProj(term(pre), c, idp)(N)
     case App(Ident("#"), Tree.Tup(Sel(pre, Ident(name)) :: App(Ident(proj), args) :: Nil)) =>
       term(App(App(Ident("#"), Tree.Tup(Sel(pre, Ident(name)) :: Ident(proj) :: Nil)), args))
     case App(Ident("!"), Tree.Tup(rhs :: Nil)) =>
@@ -369,9 +376,7 @@ extends Importer:
     case Sel(pre, nme) =>
       val preTrm = term(pre)
       val sym = resolveField(nme, preTrm.symbol, nme)
-      if inAppPrefix
-      then Term.SynthSel(preTrm, nme)(sym)
-      else Term.Sel(preTrm, nme)(sym)
+      Term.Sel(preTrm, nme)(sym)
     case tree @ Tup(fields) =>
       Term.Tup(fields.map(fld(_)))(tree)
     case New(body) => // TODO handle Under

hkmc2/shared/src/main/scala/hkmc2/semantics/Term.scala

@@ -27,7 +27,7 @@ enum Term extends Statement:
   case Quoted(body: Term)
   case Unquoted(body: Term)
   case New(cls: Term, args: Ls[Term])
-  case SelProj(prefix: Term, cls: Term, proj: Tree.Ident)
+  case SelProj(prefix: Term, cls: Term, proj: Tree.Ident)(val sym: Opt[FieldSymbol])
   case Asc(term: Term, ty: Term)
   case CompType(lhs: Term, rhs: Term, pol: Bool)
   case Neg(rhs: Term)
@@ -46,6 +46,7 @@ enum Term extends Statement:
     case Ref(sym) => S(sym)
     case sel: SynthSel => sel.sym
     case sel: Sel => sel.sym
+    case sel: SelProj => sel.sym
     case _ => N
 
   def describe: Str = this match
@@ -84,7 +85,7 @@ import Term.*
 sealed trait Statement extends AutoLocated with ProductWithExtraInfo:
 
   def extraInfo: Str = this match
-    case trm @ (_: Sel | _: SynthSel) => trm.symbol.mkString
+    case trm @ (_: Sel | _: SynthSel | _: SelProj) => trm.symbol.mkString
     case _ => ""
 
   def subStatements: Ls[Statement] = this match
@@ -205,6 +206,7 @@ sealed trait Statement extends AutoLocated with ProductWithExtraInfo:
         cls.paramsOpt.fold("")(_.toString)} ${cls.body}"
     case Import(sym, file) => s"import ${sym} from ${file}"
     case Annotated(annotation, target) => s"@${annotation.showDbg} ${target.showDbg}"
+    case Throw(res) => s"throw ${res.showDbg}"
 
 final case class LetDecl(sym: LocalSymbol, annotations: Ls[Term]) extends Statement
 

hkmc2/shared/src/main/scala/hkmc2/syntax/Tree.scala

@@ -340,4 +340,6 @@ trait TypeDefImpl(using semantics.Elaborator.State) extends TypeOrTermDef:
         case (S(spd), id, _) => ??? // spreads are not allowed in class parameters
         case (N, id, _) => semantics.TermSymbol(ParamBind, symbol.asClsLike, id)
       .toList
+
+  lazy val allSymbols = definedSymbols ++ clsParams.map(s => s.nme -> s).toMap
 

hkmc2/shared/src/test/mlscript-compile/bbml/Predef.mjs

@@ -1,23 +1,26 @@
 const Predef$class = class Predef {
   constructor() {}
-  checkArgs(functionName, expected, got) {
-    let scrut, name, scrut1, tmp, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6;
-    scrut = got != expected;
+  checkArgs(functionName, expected, isUB, got) {
+    let scrut, name, scrut1, tmp, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8, tmp9;
+    tmp = got < expected;
+    tmp1 = got > expected;
+    tmp2 = isUB && tmp1;
+    scrut = tmp || tmp2;
     if (scrut) {
       scrut1 = functionName.length > 0;
       if (scrut1) {
-        tmp = " '".concat(functionName) ?? null;
-        tmp1 = tmp.concat("'") ?? null;
+        tmp3 = " '" + functionName;
+        tmp4 = tmp3 + "'";
       } else {
-        tmp1 = "";
+        tmp4 = "";
       }
-      name = tmp1;
-      tmp2 = "Function".concat(name) ?? null;
-      tmp3 = tmp2.concat(" expected ") ?? null;
-      tmp4 = tmp3.concat(expected) ?? null;
-      tmp5 = tmp4.concat(" arguments but got ") ?? null;
-      tmp6 = tmp5.concat(got) ?? null;
-      throw new Error.class(tmp6);
+      name = tmp4;
+      tmp5 = "Function" + name;
+      tmp6 = tmp5 + " expected ";
+      tmp7 = tmp6 + expected;
+      tmp8 = tmp7 + " arguments but got ";
+      tmp9 = tmp8 + got;
+      throw globalThis.Error(tmp9) ?? null;
     } else {
       return null;
     }

hkmc2/shared/src/test/mlscript-compile/bbml/Predef.mls

@@ -1,7 +1,7 @@
 module Predef with ...
 
-fun checkArgs(functionName, expected, got) =
-  if got != expected then
-    let name = if functionName.Str#length > 0 then " '".Str#concat(functionName).Str#concat("'") else ""
-    throw new Error("Function".Str#concat(name).Str#concat(" expected ").Str#concat(expected).Str#concat(" arguments but got ").Str#concat(got))
-  else ()
+fun checkArgs(functionName, expected, isUB, got) =
+  if got < expected || isUB && got > expected do
+    let name = if functionName.length > 0 then " '" + functionName + "'" else ""
+    throw globalThis.Error("Function" + name + " expected " + expected + " arguments but got " + got)
+

hkmc2/shared/src/test/mlscript/basics/ExplicitSelections.mls

@@ -0,0 +1,22 @@
+:js
+
+
+class Foo() with
+  val x = 1
+  fun f() = x + 1
+
+
+Foo().x
+//│ = 1
+
+Foo().Foo#x
+//│ = 1
+
+
+Foo().f()
+//│ = 2
+
+Foo().Foo#f()
+//│ = 2
+
+

hkmc2/shared/src/test/mlscript/bbml/bbErrors.mls

@@ -24,14 +24,39 @@
 //│ ╔══[ERROR] Name not found: Foo
 //│ ║  l.23: 	(1).Foo#a()
 //│ ╙──      	   ^^^^
+//│ ╔══[ERROR] Identifier `Foo` does not name a known class symbol.
+//│ ║  l.23: 	(1).Foo#a()
+//│ ╙──      	   ^^^^
 //│ ═══[ERROR] Not a valid class: <error>
 //│ Type: ⊥
 
 
+fun Oops() = 1
+Oops().Oops#a()
+//│ ╔══[ERROR] Identifier `Oops` does not name a known class symbol.
+//│ ║  l.35: 	Oops().Oops#a()
+//│ ╙──      	      ^^^^^
+//│ ╔══[ERROR] Not a valid class: selection
+//│ ║  l.35: 	Oops().Oops#a()
+//│ ╙──      	      ^^^^^
+//│ Type: ⊥
+
+class Oops2()
+(new Oops2()).Oops2#a()
+//│ ╔══[ERROR] Class 'Oops2' does not contain member 'a'.
+//│ ║  l.45: 	(new Oops2()).Oops2#a()
+//│ ╙──      	                    ^
+//│ ╔══[ERROR] a is not a valid member in class Oops2
+//│ ║  l.45: 	(new Oops2()).Oops2#a()
+//│ ╙──      	     ^^^^^^^^^^^^^^^^
+//│ Type: ⊥
+
+
+
 fun inc(x) = x + 1
 inc("oops")
 //│ ╔══[ERROR] Type error in string literal with expected type 'x
-//│ ║  l.32: 	inc("oops")
+//│ ║  l.57: 	inc("oops")
 //│ ║        	    ^^^^^^
 //│ ╟── because: cannot constrain  Str  <:  'x
 //│ ╟── because: cannot constrain  Str  <:  'x
@@ -41,7 +66,7 @@ inc("oops")
 fun inc(x) = x + 1
 inc : Int
 //│ ╔══[ERROR] Type error in selection with expected type Int
-//│ ║  l.42: 	inc : Int
+//│ ║  l.67: 	inc : Int
 //│ ║        	^^^
 //│ ╙── because: cannot constrain  'x -> Int  <:  Int
 //│ Type: Int

hkmc2/shared/src/test/mlscript/bbml/bbRec.mls

@@ -45,7 +45,7 @@ new Foo(123)
 
 :todo proper error
 fun f(x) = f(Foo.a(x))
-//│ ╔══[ERROR] Term shape not yet supported by BbML: SynthSel(SynthSel(Ref(globalThis:block#5),Ident(Foo)),Ident(a))
+//│ ╔══[ERROR] Term shape not yet supported by BbML: Sel(SynthSel(Ref(globalThis:block#5),Ident(Foo)),Ident(a))
 //│ ║  l.47: 	fun f(x) = f(Foo.a(x))
 //│ ╙──      	             ^^^^^
 //│ Type: ⊤

hkmc2/shared/src/test/mlscript/codegen/Do.mls

@@ -41,7 +41,7 @@ val f = case
 //│ Desugared:
 //│ >  if
 //│ >    caseScrut is 0 then "null"
-//│ >    let $doTemp = globalThis:import#Prelude#666(.)console‹member:console›(.)log("non-null")
+//│ >    let $doTemp = globalThis:import#Prelude#666(.)console‹member:console›.log("non-null")
 //│ >    caseScrut is 1 then "unit"
 //│ >    let res = "other"
 //│ >    let $doTemp = member:Predef#666(.)print‹member:print›(res#666)

hkmc2/shared/src/test/mlscript/decls/Prelude.mls

@@ -7,7 +7,9 @@ declare class Object
 declare class Bool
 declare class Int
 declare class Num
-declare class Str
+declare class Str with
+  fun length: Int
+  fun concat: Str -> Str
 declare class Set
 declare class Error(msg)
 

hkmc2/shared/src/test/mlscript/nofib/NofibPrelude.mls

@@ -20,7 +20,7 @@ class Lazy[out A](init: () -> A) with
         set cached = Some(v)
         v
 fun lazy(x) = Lazy(x)
-fun force(x) = if x is Lazy then x.get()
+fun force(x) = if x is Lazy then x.Lazy#get()
 
 abstract class List[out T]: Cons[T] | Nil
 class (::) Cons[out T](head: T, tail: List[T]) extends List[T] with