Drop '=' when parsing alt symbols

src/preserves/schemas.nim

@@ -82,7 +82,10 @@ proc `$`*(n: SchemaNode): string =
     result.add join(n.nodes, " & ")
   of snkAlt:
     case n.altBranch.kind
-    of snkRecord, snkRef, snkLiteral:
+    of snkRecord, snkRef:
+      result.add $n.altBranch
+    of snkLiteral:
+      result.add '='
       result.add $n.altBranch
     else:
       result.add '@'
@@ -252,14 +255,14 @@ const parser = peg("Schema", p: ParseState):
     pushStack n
 
   AltLiteralPattern <-
-      Preserves.Boolean |
-      Preserves.Float |
-      Preserves.Double |
-      Preserves.SignedInteger |
-      Preserves.String |
-      Preserves.Symbol:
+      >Preserves.Boolean |
+      >Preserves.Float |
+      >Preserves.Double |
+      >Preserves.SignedInteger |
+      >Preserves.String |
+      '=' * >Preserves.Symbol:
     let
-      branch = SchemaNode(kind: snkLiteral, value: parsePreserves($0))
+      branch = SchemaNode(kind: snkLiteral, value: parsePreserves($1))
       label = case branch.value.kind
         of pkBoolean:
           if branch.value.bool: "true" else: "false"