Add annotation for table-from-raw-array(), checking arg is indeed a raw array of rows

src/arr/trove/tables.arr

@@ -1,5 +1,5 @@
 provide:
-  * hiding (is-kv-pairs),
+  * hiding (is-kv-pairs, is-raw-array-of-rows),
   type *
 end
 
@@ -88,7 +88,11 @@ fun empty-table(col-names :: List<String>) -> Table:
   end
 end
 
-fun table-from-raw-array(arr):
+fun is-raw-array-of-rows(ra :: RawArray<Any>) -> Boolean:
+  raw-array-fold(lam(base, elt, _): base and is-row(elt) end, true, ra, 0)
+end
+
+fun table-from-raw-array(arr :: RawArray<Any>%(is-raw-array-of-rows)) -> Table:
   col-names = raw-array-get(arr, 0).get-column-names()
   with-cols = empty-table(col-names)
   for raw-array-fold(t from with-cols, r from arr, _ from 0):

tests/pyret/tests/test-tables.arr

@@ -687,8 +687,24 @@ check "table-from-rows":
   t4 = table-from-rows.make(raw-array-from-list(new-row-list))
 
   nothing does-not-raise # Dummy test to avoid well-formedness errors in the previous row
-end
 
+  [table-from-rows:
+    [list:
+      [raw-row: {"A"; 5}, {"B"; 7}, {"C"; 8}],
+      [raw-row: {"A"; 1}, {"B"; 2}, {"C"; 3}]]]
+    raises "is-raw-array-of-rows"
+
+  [table-from-rows:
+    1, [raw-row: {"A"; 1}, {"B"; 2}],
+    false, [raw-row: {"A"; 3}, {"B"; 4}],
+    "non-row string", [raw-row: {"A"; 5}, {"B"; 6}]]
+    raises "is-raw-array-of-rows"
+
+  [table-from-rows:
+    [raw-row: 5, {"B"; 7}, {"C"; 8}],
+    [raw-row: {"A"; 1}, {"B"; 2}, {"C"; 3}]]
+    raises "KeyValPair"
+end
 
 table-from-column = TS.table-from-column
 table-from-columns = TS.table-from-columns