@@ -279,7 +279,7 @@ if symbol == "return":
       raise MinReturnException(msg: "return symbol found")
     i.debug("push: $#" % [symbol])
     let op = i.scope.getSymbol(symbol)
-    if not op.isNull:
+    if not op.isUnknown:
       i.debug("push: symbol found: $#" % [symbol])
       i.apply op, symbol
     else:
@@ -288,7 +288,7 @@ if symbol.len > 1 and symbol[symbol.len-1] == '!':
         i.debug("push - checking auto-popping symbol: $#" % [symbol])
         let apSymbol = symbol[0..symbol.len-2]
         let apOp = i.scope.getSymbol(apSymbol)
-        if not apOp.isNull:
+        if not apOp.isUnknown:
           i.apply apOp
           discard i.pop
       else:

@@ -45,6 +45,7 @@ minDictionary,
     minString,
     minSymbol,
     minNull,
+    minUnknown,
     minBool
   MinEventKind* = enum   ## enumeration of all events that may occur when parsing
     eMinError,           ## an error ocurred during parsing
@@ -83,6 +84,7 @@ filename*: string
     outerSym*: string
     docComment*: string
     case kind*: MinKind
+      of minUnknown: discard
       of minNull: discard
       of minInt: intVal*: BiggestInt
       of minFloat: floatVal*: BiggestFloat
@@ -605,7 +607,7 @@ else: raiseParsing(p, tokToStr[token])
 
 proc `$`*(a: MinValue): string {.inline.} =
   case a.kind:
-    of minNull:
+    of minNull, minUnknown:
       return "null"
     of minBool:
       return $a.boolVal
@@ -655,7 +657,7 @@ return "[" & a.cmdVal & "]"
 
 proc `$$`*(a: MinValue): string {.inline.} =
   case a.kind:
-    of minNull:
+    of minNull, minUnknown:
       return "null"
     of minBool:
       return $a.boolVal
@@ -891,6 +893,9 @@ stdout.flushFile()
 
 # Predicates
 
+proc isUnknown*(s: MinValue): bool =
+  return s.kind == minUnknown
+
 proc isNull*(s: MinValue): bool =
   return s.kind == minNull
 
@@ -1016,6 +1021,9 @@ 
 proc isNull*(op: MinOperator): bool =
   return op.kind == minValOp and op.val.kind == minNull
 
+proc isUnknown*(op: MinOperator): bool =
+  return op.kind == minValOp and op.val.kind == minUnknown
+
 proc getSymbol*(scope: ref MinScope, key: string): MinOperator =
   debug "getSymbol: $#" % [key]
   if scope.symbols.hasKey(key):
@@ -1026,7 +1034,7 @@ return getSymbolFromPath(scope, keys)
   else:
     if scope.parent.isNil:
       debug("Unable to retrieve symbol '$1' (not found)." % key)
-      return MinOperator(kind: minValOp, val: MinValue(kind: minNull))
+      return MinOperator(kind: minValOp, val: MinValue(kind: minUnknown))
     return scope.parent.getSymbol(key)
 
 proc getSymbolFromPath(scope: ref MinScope, keys: var seq[string]): MinOperator =

@@ -130,7 +130,7 @@ p(part["value"].getStr, fgCyan)
 
 proc pv(i:In, item: MinValue) =
   case item.kind
-  of minNull, minBool, minFloat, minInt:
+  of minNull, minBool, minFloat, minInt, minUnknown:
     p($item, fgGreen)
   of minSymbol:
     i.printSymbol($item)

@@ -127,7 +127,7 @@ proc `%`*(i: In, a: MinValue): JsonNode =
   case a.kind:
     of minBool:
       return %a.boolVal
-    of minNull:
+    of minNull, minUnknown:
       return newJNull()
     of minSymbol:
       return %(";sym:$1" % [a.getstring])
@@ -251,11 +251,11 @@ if split[0] == "dict":
           if value.isTypedDictionary(split[1]):
             return true
         return false
-      elif not taSym.isNull:
+      elif not taSym.isUnknown:
         # Custom type alias
         let element = taSym.val.getString
         return i.validateValueType(element, value)
-      elif not i.scope.getSymbol(tc).isNull:
+      elif not i.scope.getSymbol(tc).isUnknown:
         # Custom type class
         var i2 = i.copy(i.filename)
         i2.withScope():
@@ -288,7 +288,7 @@ const ts = ["bool", "null", "int", "num", "flt", "quot", "dict", "'sym",
       "sym", "str", "a"]
   if ts.contains(s):
     return true
-  if not i.scope.getSymbol("typeclass:$#" % s).isNull:
+  if not i.scope.getSymbol("typeclass:$#" % s).isUnknown:
     return true
   for ta in s.split("|"):
     for to in ta.split("&"):
@@ -298,10 +298,10 @@ return false
       if to[0] == '!':
         tt = to[1..to.len-1]
       if not ts.contains(tt) and not tt.startsWith("dict:") and
-          i.scope.getSymbol("typeclass:$#" % tt).isNull:
+          i.scope.getSymbol("typeclass:$#" % tt).isUnknown:
         let ta = "typealias:$#" % tt
         let taSym = i.scope.getSymbol(ta)
-        if not taSym.isNull:
+        if not taSym.isUnknown:
           return i.validType(taSym.val.getString)
         return false
   return true

@@ -21,7 +21,7 @@ of minString:
       return "str"
     of minSymbol:
       return "sym"
-    of minNull:
+    of minNull, minUnknown:
       return "null"
     of minBool:
       return "bool"

@@ -350,7 +350,7 @@ var iv = inVals[k]
           i.scope.symbols[inVars[k]] = MinOperator(kind: minValOp, sealed: false, val: iv)
         # Inject variables for mapped outputs
         for k in 0..outVars.len-1:
-          i.scope.symbols[outVars[k]] = MinOperator(kind: minValOp, sealed: false, val: @[newNull()].newVal)
+          i.scope.symbols[outVars[k]] = MinOperator(kind: minValOp, sealed: false, val: newNull())
         # Actually execute the body of the operator
         if DEV:
           var endSnapshot: seq[MinValue]
@@ -405,7 +405,7 @@ doc["description"] = %i.currSym.docComment.strip
     if ["symbol", "typeclass", "constructor"].contains(t):
       if i.scope.symbols.hasKey(n) and i.scope.symbols[n].sealed:
         raiseUndefined("Attempting to redefine sealed symbol '$1'" % [n])
-      i.scope.symbols[n] = MinOperator(kind: minProcOp, prc: p, sealed: false, doc: doc)
+      i.scope.symbols[n] = MinOperator(kind: minProcOp, prc: p, sealed: false, doc: doc, lambda: true)
     else:
       if i.scope.sigils.hasKey(n) and i.scope.sigils[n].sealed:
         raiseUndefined("Attempting to redefine sealed sigil '$1'" % [n])
@@ -452,7 +452,7 @@ i.push q.newVal
 
   def.symbol("defined-symbol?") do (i: In):
     let vals = i.expect("'sym")
-    i.push((not i.scope.getSymbol(vals[0].getString).isNull).newVal)
+    i.push((not i.scope.getSymbol(vals[0].getString).isUnknown).newVal)
 
   def.symbol("defined-sigil?") do (i: In):
     let vals = i.expect("'sym")
@@ -656,7 +656,7 @@ def.symbol("symbol-help") do (i: In):
     let vals = i.expect("'sym")
     let s = vals[0].getString
     let sym = i.scope.getSymbol(s)
-    if not sym.isNull:
+    if not sym.isUnknown:
       if not sym.doc.isNil and sym.doc.kind == JObject:
         var doc = i.fromJson(sym.doc)
         doc.objType = "help"
@@ -709,7 +709,7 @@ for l in lines:
             echo "  " & l
       echo "==="
     let sym = i.scope.getSymbol(s)
-    if not sym.isNull:
+    if not sym.isUnknown:
       found = true
       if not sym.doc.isNil and sym.doc.kind == JObject:
         foundDoc = true