diff --git a/compiler/src/prog8/ast/expressions/AstExpressions.kt b/compiler/src/prog8/ast/expressions/AstExpressions.kt
index 857a0447c..996130b7d 100644
--- a/compiler/src/prog8/ast/expressions/AstExpressions.kt
+++ b/compiler/src/prog8/ast/expressions/AstExpressions.kt
@@ -63,7 +63,27 @@ class PrefixExpression(val operator: String, var expression: Expression, overrid
     override fun accept(visitor: IAstModifyingVisitor) = visitor.visit(this)
     override fun accept(visitor: IAstVisitor) = visitor.visit(this)
     override fun referencesIdentifiers(vararg name: String) = expression.referencesIdentifiers(*name)
-    override fun inferType(program: Program): InferredTypes.InferredType = expression.inferType(program)
+    override fun inferType(program: Program): InferredTypes.InferredType {
+        val inferred = expression.inferType(program)
+        return when(operator) {
+            "+" -> inferred
+            "~", "not" -> {
+                when(inferred.typeOrElse(DataType.STRUCT)) {
+                    in ByteDatatypes -> InferredTypes.knownFor(DataType.UBYTE)
+                    in WordDatatypes -> InferredTypes.knownFor(DataType.UWORD)
+                    else -> inferred
+                }
+            }
+            "-" -> {
+                when(inferred.typeOrElse(DataType.STRUCT)) {
+                    in ByteDatatypes -> InferredTypes.knownFor(DataType.BYTE)
+                    in WordDatatypes -> InferredTypes.knownFor(DataType.WORD)
+                    else -> inferred
+                }
+            }
+            else -> throw FatalAstException("weird prefix expression operator")
+        }
+    }
 
     override fun toString(): String {
         return "Prefix($operator $expression)"
diff --git a/compiler/src/prog8/ast/processing/AstChecker.kt b/compiler/src/prog8/ast/processing/AstChecker.kt
index 1b629c23c..da6e1565e 100644
--- a/compiler/src/prog8/ast/processing/AstChecker.kt
+++ b/compiler/src/prog8/ast/processing/AstChecker.kt
@@ -144,7 +144,6 @@ internal class AstChecker(private val program: Program,
                                 checkResult.add(ExpressionError("uword loop variable can only loop over unsigned bytes, words or strings", forLoop.position))
                         }
                         DataType.BYTE -> {
-                            // TODO fix this, it should allow:  for bb in [1,2,3]
                             if(iterableDt!= DataType.BYTE && iterableDt!= DataType.ARRAY_B)
                                 checkResult.add(ExpressionError("byte loop variable can only loop over bytes", forLoop.position))
                         }
@@ -1200,6 +1199,10 @@ internal class AstChecker(private val program: Program,
             when (it) {
                 is NumericLiteralValue -> it.number.toInt()
                 is AddressOf -> it.identifier.heapId(program.namespace)
+                is TypecastExpression -> {
+                    val constVal = it.expression.constValue(program)
+                    constVal?.cast(it.type)?.number?.toInt() ?: -9999999
+                }
                 else -> -9999999
             }
         }
diff --git a/compiler/src/prog8/ast/processing/AstIdentifiersChecker.kt b/compiler/src/prog8/ast/processing/AstIdentifiersChecker.kt
index 93637725a..fc159ce2e 100644
--- a/compiler/src/prog8/ast/processing/AstIdentifiersChecker.kt
+++ b/compiler/src/prog8/ast/processing/AstIdentifiersChecker.kt
@@ -235,10 +235,12 @@ internal class AstIdentifiersChecker(private val program: Program) : IAstModifyi
                 // fix the datatype of the array (also on the heap) to the 'biggest' datatype in the array
                 // (we don't know the desired datatype here exactly so we guess)
                 val datatype = determineArrayDt(array.value)
-                val litval2 = array.cast(datatype)!!
-                litval2.parent = array.parent
-                // finally, replace the literal array by a identifier reference.
-                makeIdentifierFromRefLv(litval2)
+                val litval2 = array.cast(datatype)
+                if(litval2!=null) {
+                    litval2.parent = array.parent
+                    // finally, replace the literal array by a identifier reference.
+                    makeIdentifierFromRefLv(litval2)
+                } else array
             }
         }
         return array
@@ -366,10 +368,15 @@ internal fun fixupArrayEltDatatypes(array: ArrayLiteralValue, program: Program):
 
     // convert values and array type
     val elementType = ArrayElementTypes.getValue(dt)
-    val values = array.value.map { (it as NumericLiteralValue).cast(elementType) as Expression}.toTypedArray()
-    val array2 = ArrayLiteralValue(dt, values, array.position)
-    array2.linkParents(array.parent)
-    return array2
+    val allNumerics = array.value.all { it is NumericLiteralValue }
+    if(allNumerics) {
+        val values = array.value.map { (it as NumericLiteralValue).cast(elementType) as Expression }.toTypedArray()
+        val array2 = ArrayLiteralValue(dt, values, array.position)
+        array2.linkParents(array.parent)
+        return array2
+    }
+
+    return array
 }
 
 internal fun fixupArrayEltDatatypesFromVardecl(array: ArrayLiteralValue, vardecl: VarDecl): ArrayLiteralValue {
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index b9a98f2de..fb643b9aa 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -4,7 +4,6 @@ TODO
 
 - @"zzz"  screencode encoded strings  + add this to docs too
 - add 'void' keyword to explicitly ignore subroutine return values
-- allow:  for bb in [1,2,3]  + docs?
 
 
 Memory Block Operations integrated in language?