Add a test comparing the reference implemntations of foldl,

`scanl` and `iterate` to their primitive implementations.

tests/regression/reference.cry

@@ -0,0 +1,12 @@
+import Cryptol::Reference as Ref
+
+// NB, using subtraction here because is is not commutative or associative
+
+property foldl_eq (z:Integer) (xs:[10]Integer) =
+  foldl (-) z xs == Ref::foldl (-) z xs
+
+property scanl_eq (z:Integer) (xs:[10]Integer) =
+  scanl (-) z xs == Ref::scanl (-) z xs
+
+property iterate_eq (z:Integer) (i:[8]) =
+  (iterate (\x -> x + 1) z)@i == (Ref::iterate (\x -> x + 1) z)@i

tests/regression/reference.icry

@@ -0,0 +1,10 @@
+:l reference.cry
+
+:set tests=1000
+:check
+
+:set prover=sbv-z3
+:prove
+
+:set prover=w4-z3
+:prove

tests/regression/reference.icry.stdout

@@ -0,0 +1,22 @@
+Loading module Cryptol
+Loading module Cryptol
+Loading module Cryptol::Reference
+Loading module Main
+property foldl_eq Using random testing.
+Testing... Passed 1000 tests.
+property scanl_eq Using random testing.
+Testing... Passed 1000 tests.
+property iterate_eq Using random testing.
+Testing... Passed 1000 tests.
+:prove foldl_eq
+	Q.E.D.
+:prove scanl_eq
+	Q.E.D.
+:prove iterate_eq
+	Q.E.D.
+:prove foldl_eq
+	Q.E.D.
+:prove scanl_eq
+	Q.E.D.
+:prove iterate_eq
+	Q.E.D.