[RFC] Add properties to List for byte-based encodings/hashes

pkl-core/src/main/java/org/pkl/core/runtime/VmList.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -136,6 +136,15 @@ public boolean isEmpty() {
     return rrbt.isEmpty();
   }
 
+  @TruffleBoundary
+  public byte[] getBytes() {
+    var result = new byte[rrbt.size()];
+    for (var i = 0; i < rrbt.size(); i++) {
+      result[i] = VmUtils.checkByte(rrbt.get(i));
+    }
+    return result;
+  }
+
   @Override
   @TruffleBoundary
   public boolean isLengthOne() {

pkl-core/src/main/java/org/pkl/core/runtime/VmUtils.java

@@ -485,6 +485,14 @@ public static void checkPositive(long n) {
     }
   }
 
+  public static byte checkByte(Object n) {
+    if (n instanceof Long l && l >= 0 && l <= 255) {
+      return l.byteValue();
+    }
+    CompilerDirectives.transferToInterpreter();
+    throw new VmExceptionBuilder().evalError("expectedByte", n).build();
+  }
+
   public static Source loadSource(ResolvedModuleKey resolvedKey) {
     try {
       var text = resolvedKey.loadSource();

pkl-core/src/main/java/org/pkl/core/stdlib/base/ListNodes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.nodes.LoopNode;
+import java.util.Base64;
 import org.pkl.core.ast.expression.binary.*;
 import org.pkl.core.ast.internal.IsInstanceOfNode;
 import org.pkl.core.ast.internal.IsInstanceOfNodeGen;
@@ -28,6 +29,7 @@
 import org.pkl.core.stdlib.base.CollectionNodes.CompareByNode;
 import org.pkl.core.stdlib.base.CollectionNodes.CompareNode;
 import org.pkl.core.stdlib.base.CollectionNodes.CompareWithNode;
+import org.pkl.core.util.ByteArrayUtils;
 import org.pkl.core.util.EconomicSets;
 
 // duplication between ListNodes and SetNodes is "intentional"
@@ -51,6 +53,45 @@ protected boolean eval(VmList self) {
     }
   }
 
+  public abstract static class md5 extends ExternalPropertyNode {
+    @TruffleBoundary
+    @Specialization
+    protected String eval(VmList self) {
+      return ByteArrayUtils.md5(self.getBytes());
+    }
+  }
+
+  public abstract static class sha1 extends ExternalPropertyNode {
+    @TruffleBoundary
+    @Specialization
+    protected String eval(VmList self) {
+      return ByteArrayUtils.sha1(self.getBytes());
+    }
+  }
+
+  public abstract static class sha256 extends ExternalPropertyNode {
+    @TruffleBoundary
+    @Specialization
+    protected String eval(VmList self) {
+      return ByteArrayUtils.sha256(self.getBytes());
+    }
+  }
+
+  public abstract static class sha256Int extends ExternalPropertyNode {
+    @TruffleBoundary
+    @Specialization
+    protected long eval(VmList self) {
+      return ByteArrayUtils.sha256Int(self.getBytes());
+    }
+  }
+
+  public abstract static class base64 extends ExternalPropertyNode {
+    @Specialization
+    protected String eval(VmList self) {
+      return Base64.getEncoder().encodeToString(self.getBytes());
+    }
+  }
+
   public abstract static class lastIndex extends ExternalPropertyNode {
     @Specialization
     protected long eval(VmList self) {

pkl-core/src/main/resources/org/pkl/core/errorMessages.properties

@@ -542,6 +542,9 @@ Int value `{0}` is too large (only Int32 supported here).
 expectedPositiveNumber=\
 Expected a positive number, but got `{0}`.
 
+expectedByte=\
+Expected an Int value between 0 and 255, but got `{0}`.
+
 cannotFindResource=\
 Cannot find resource `{0}`.
 

stdlib/base.pkl

@@ -1,5 +1,5 @@
 //===----------------------------------------------------------------------===//
-// Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+// Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -2794,6 +2794,40 @@ external class List<out Element> extends Collection<Element> {
 
   external isEmpty: Boolean
 
+  /// The [MD5](https://en.wikipedia.org/wiki/MD5)
+  /// hash of this list's byte sequence as hexadecimal string.
+  ///
+  /// MD5 is cryptographically broken and should not be used for secure applications.
+  /// 
+  /// Throws an error when [Element] is not [UInt8].
+  external md5: String
+
+  /// The [SHA-1](https://en.wikipedia.org/wiki/SHA-1)
+  /// hash of this list's byte sequence.
+  ///
+  /// SHA-1 is cryptographically broken and should not be used for secure applications.
+  /// 
+  /// Throws an error when [Element] is not [UInt8].
+  external sha1: String
+
+  /// The [SHA-256](https://en.wikipedia.org/wiki/SHA-2)
+  /// cryptographic hash of this list's byte sequence
+  /// as hexadecimal string.
+  /// 
+  /// Throws an error when [Element] is not [UInt8].
+  external sha256: String
+
+  /// The first 64 bits of the [SHA-256](https://en.wikipedia.org/wiki/SHA-2)
+  /// cryptographic hash of this list's byte sequence.
+  /// 
+  /// Throws an error when [Element] is not [UInt8].
+  external sha256Int: Int
+
+  /// The Base64 encoding of this string's UTF-8 byte sequence.
+  /// 
+  /// Throws an error when [Element] is not [UInt8].
+  external base64: String
+
   /// The index of the last element in this list (same as `length - 1`).
   ///
   /// Returns `-1` for an empty list.