Enforce rules on module arguments

Author: FlandiaYingman

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

@@ -259,7 +259,34 @@ extends Importer:
       term(rhs)
     case tree @ App(lhs, rhs) =>
       val sym = FlowSymbol("‹app-res›", nextUid)
-      Term.App(term(lhs), term(rhs))(tree, sym)
+      val lt = term(lhs)
+      val rt = term(rhs)
+
+      // Check if module arguments match module parameters
+      val args = rt match
+        case Term.Tup(fields) => S(fields)
+        case _ => N
+      val params = lt.symbol
+        .collect:
+          case sym: BlockMemberSymbol => sym.trmTree
+        .flatten
+        .collect:
+          case td: TermDef => td.paramLists.headOption
+        .flatten
+      for
+        (args, params) <- (args zip params)
+        (arg, param) <- (args zip params.fields)
+      do 
+        val argMod = arg.flags.mod
+        val paramMod = param match
+          case Tree.TypeDef(Mod, _, N, N) => true
+          case _ => false
+        if argMod && !paramMod then raise:
+          ErrorReport:
+            msg"Only module parameters may receive module arguments (values)." -> 
+            arg.toLoc :: Nil
+      
+      Term.App(lt, rt)(tree, sym)
     case Sel(pre, nme) =>
       val preTrm = term(pre)
       val sym = resolveField(nme, preTrm.symbol, nme)
@@ -356,9 +383,10 @@ extends Importer:
       Fld(FldFlags.empty, term(lhs), S(term(rhs)))
     case _ => 
       val t = term(tree)
-      t.symbol.flatMap(_.asMod) match
-        case S(_) => Fld(FldFlags.empty.copy(mod = true), t, N)
-        case N => Fld(FldFlags.empty, t, N)
+      val flags = FldFlags.empty
+      if ModuleChecker.evalsToModule(t) 
+      then Fld(flags.copy(mod = true), t, N)
+      else Fld(flags, t, N)
 
   def unit: Term.Lit = Term.Lit(UnitLit(true))
 

hkmc2/shared/src/test/mlscript-compile/Stack.mls

@@ -5,7 +5,7 @@
 module Stack with ...
 
 class (::) Cons[A](head: A, tail)
-module Nil
+object Nil
 
 fun isEmpty(xs) = xs is Nil
 

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

@@ -6,48 +6,65 @@ class C with {
 module M with {
   // module method foo
   fun foo(x) = x
+  // module method self
+  fun self(): module M = M
 }
 
 :e
 fun f1(module m)
 //│ ╔══[ERROR] Module parameters must have explicit types.
-//│ ║  l.12: 	fun f1(module m)
+//│ ║  l.14: 	fun f1(module m)
 //│ ╙──      	              ^
 
 :e
 fun f2[T](module m: T)
 //│ ╔══[ERROR] Module parameters must have concrete types.
-//│ ║  l.18: 	fun f2[T](module m: T)
+//│ ║  l.20: 	fun f2[T](module m: T)
 //│ ╙──      	                 ^^^^
 
 :e
 module N with {
   fun f3() = M
 }
 //│ ╔══[ERROR] Function returning module values must have explicit return types.
-//│ ║  l.25: 	  fun f3() = M
+//│ ║  l.27: 	  fun f3() = M
 //│ ╙──      	      ^^^^
 
 :e
 module N with {
   fun f4[T](): module T = M
 }
 //│ ╔══[ERROR] Function returning module values must have explicit return types.
-//│ ║  l.33: 	  fun f4[T](): module T = M
+//│ ║  l.35: 	  fun f4[T](): module T = M
 //│ ╙──      	      ^^^^^^^^^^^^^^^^^
 
 :e
 module N with {
   fun f5(): M = M
 }
 //│ ╔══[ERROR] The return type of functions returning module values must be prefixed with module keyword.
-//│ ║  l.41: 	  fun f5(): M = M
+//│ ║  l.43: 	  fun f5(): M = M
 //│ ╙──      	      ^^^^^^^
 
+
+fun f6(m: M)
+
+:e
+f6(M)
+//│ ╔══[ERROR] Only module parameters may receive module arguments (values).
+//│ ║  l.53: 	f6(M)
+//│ ╙──      	   ^
+
+:e
+f6(M.self())
+//│ ╔══[ERROR] Only module parameters may receive module arguments (values).
+//│ ║  l.59: 	f6(M.self())
+//│ ╙──      	   ^^^^^^^^
+
 :e
 fun f7(): module M
 //│ ╔══[ERROR] Only module methods may return module values.
-//│ ║  l.48: 	fun f7(): module M
+//│ ║  l.65: 	fun f7(): module M
 //│ ╙──      	    ^^^^^^^^^^^^^^
 
 

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

@@ -6,7 +6,7 @@
 
 class Some[out A](value: A)
 
-module None
+object None
 
 
 :sjs

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

@@ -1,7 +1,7 @@
 :js
 
 
-module Foo
+object Foo
 
 fun test(x) = x is Foo
 
@@ -10,7 +10,7 @@ test(Foo)
 
 
 fun foo() =
-  module Foo
+  object Foo
   Foo is Foo
 
 foo()

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

@@ -3,7 +3,7 @@
 
 // TODO could use `globalThis.Example` instead of `this` in the generated code
 :sjs
-module Example with
+object Example with
   val a = 456
   fun f(x) = [x, a]
 //│ JS:

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

@@ -2,7 +2,7 @@
 
 
 class Some(value)
-module None
+object None
 
 
 :sjs

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

@@ -4,7 +4,7 @@
 //│ Imported 2 member(s)
 
 
-module Example with
+object Example with
   val a = 1
   fun f(x) = [x, a]
 

hkmc2/shared/src/test/mlscript/ucs/examples/BinarySearchTree.mls

@@ -14,7 +14,7 @@ fun abs(x) = if x < 0 then -x else x
 
 abstract class Option[T]: (Some[T] | None)
 class Some[T](val value: T) extends Option[T]
-module None extends Option[nothing]
+object None extends Option[nothing]
 
 fun (??) getOrElse(o, v) = if o is
   Some(v') then v'
@@ -24,15 +24,15 @@ let anyToString = toString
 
 abstract class List[out T]: (Cons[T] | Nil)
 class Cons[out T](val head: T, val tail: List[T]) extends List[T]
-module Nil extends List[nothing]
+object Nil extends List[nothing]
 
 fun (::) cons(head, tail) = Cons(head, tail)
 
 1 :: 2 :: 3 :: 4 :: Nil
 
 abstract class Tree[out A]: (Empty | Node[A])
 class Node[out A](value: A, left: Tree[A], right: Tree[A]) extends Tree[A]
-module Empty extends Tree
+object Empty extends Tree
 
 fun single(v) = Node(v, Empty, Empty)
 

hkmc2/shared/src/test/mlscript/ucs/examples/LeftistTree.mls

@@ -12,21 +12,21 @@ fun abs(x) = if x < 0 then -x else x
 
 abstract class Option[out T]: (Some[T] | None)
 class Some[out T](val value: T) extends Option[T]
-module None extends Option[nothing]
+object None extends Option[nothing]
 
 fun (??) getOrElse(o, v) = if o is
   Some(v') then v'
   None then v
 
 abstract class List[out T]: (Cons[T] | Nil)
 class Cons[out T](val head: T, val tail: List[T]) extends List[T]
-module Nil extends List[nothing]
+object Nil extends List[nothing]
 
 fun (::) cons(head, tail) = Cons(head, tail)
 
 abstract class Tree[out A]: (Empty | Node[A])
 class Node[out A](value: A, left: Tree[A], right: Tree[A], rank: Int) extends Tree[A]
-module Empty extends Tree[nothing]
+object Empty extends Tree[nothing]
 
 fun show(t: Tree[Any]): Str = if t is
   Node(v, l, r, _) then

hkmc2/shared/src/test/mlscript/ucs/examples/SimpleTree.mls

@@ -2,10 +2,10 @@
 
 type Option[out A] = Some[A] | None
 class Some[out A](value: A)
-module None
+object None
 
 type Tree[out A] = Node[A] | Empty
-module Empty
+object Empty
 class Node[out A](value: A, left: Tree[A], right: Tree[A])
 
 fun find(t, v) = if t is

hkmc2/shared/src/test/mlscript/ucs/general/DualOptions.mls

@@ -7,7 +7,7 @@
 
 abstract class Option[T]
 class Some[T](value: T) extends Option[T]
-module None extends Option[nothing]
+object None extends Option[nothing]
 class Pair[A, B](x: A, y: B)
 
 // All `add_n` functions should be inferred to have the same type.

hkmc2/shared/src/test/mlscript/ucs/hygiene/HygienicBindings.mls

@@ -5,15 +5,15 @@ fun error = ()
 fun (~~>) expect(a, b) = if a == b then () else error
 
 type Option[out T] = None | Some[T]
-module None
+object None
 class Some[out T](val value: T)
 
 type Either[A, B] = Left[A] | Right[B]
 class Left[A](val leftValue: A)
 class Right[B](val rightValue: B)
 
 type List[out A] = Nil | Cons[A]
-module Nil
+object Nil
 class Cons[out A](head: A, tail: List[A])
 
 fun justTrue(_) = true

hkmc2/shared/src/test/mlscript/ucs/syntax/SimpleUCS.mls

@@ -2,7 +2,7 @@
 
 abstract class Option[A]: Some[A] | None
 class Some[A](value: A) extends Option[A]
-module None extends Option
+object None extends Option
 
 abstract class Either[out A, out B]: Left[A] | Right[B]
 class Left[A](leftValue: A) extends Either[A, nothing]