update

std/core-extras.kk

@@ -83,6 +83,11 @@ pub fun maybe/(==)(m1: maybe<a>, m2: maybe<a>, ?(==): (a, a) -> e bool): e bool
     (Nothing, Nothing) -> True
     _ -> False
 
+pub fun expect( m : maybe<a>, msg: string ="", ?kk-file-line: string ) : exn a
+  match m
+    Just(a) -> a
+    Nothing -> throw(kk-file-line ++ " expected Just " ++ msg)
+
 pub fun expect-unjust( m : maybe<a>, msg: string ) : exn a
   match m
     Just(a) -> a

std/data/word-set.kk

@@ -21,6 +21,7 @@ inline fun member(s: string, t: word-set): bool
 
 named effect string-intern
   fun intern-string(x: string): istring
+  fun is-interned(x: string): bool
 
 value struct istring
   str: string
@@ -37,8 +38,14 @@ fun string-pool(): <> ev<string-intern>
         Nothing ->
           trie := add(trie, a)
           Istring(a)
+    fun is-interned(a)
+      trie.lookup(a).is-just
   r
 
+inline fun add-all(s: ev<string-intern>, xs: list<string>): exn ev<string-intern>
+  xs.foreach(fn(x) {s.intern-string(x); ()})
+  s
+
 inline fun intern(s: string): exn istring
   words.intern-string(s)