Beginning Arborix work in tricu

lib/binary.tri

@@ -3,10 +3,24 @@
 !import "bytes.tri" !Local
 
 errUnexpectedEof = 1
+errUnexpectedBytes = 2
+errUnexpectedByte = 3
 
 ok = value rest : pair true (pair value rest)
 err = code rest : pair false (pair code rest)
 
+matchResult = (errCase okCase result :
+  matchPair
+    (tag payload :
+      matchPair
+        (value rest :
+          matchBool
+            (okCase value rest)
+            (errCase value rest)
+            tag)
+        payload)
+    result)
+
 readU8 = (bytes : matchList
   (err errUnexpectedEof t)
   (h r : ok h r)
@@ -16,8 +30,47 @@ readBytesTaken = n bytes : bytesTake n bytes
 readBytesRest = n bytes : bytesDrop n bytes
 readBytesEnough? = n bytes : equal? (bytesLength (readBytesTaken n bytes)) n
 
-readBytes = (n bytes :
-  matchBool
+readBytes = (n bytes : matchBool
     (ok (readBytesTaken n bytes) (readBytesRest n bytes))
     (err errUnexpectedEof bytes)
     (readBytesEnough? n bytes))
+
+unit = t
+
+expectBytes = (expected bs :
+  matchResult
+    (code rest : err code bs)
+    (taken rest :
+      matchBool
+        (ok unit rest)
+        (err errUnexpectedBytes bs)
+        (bytesEq taken expected))
+    (readBytes (bytesLength expected) bs))
+
+expectU8 = (expected bs :
+  matchResult
+    (code rest : err code bs)
+    (actual rest :
+      matchBool
+        (ok unit rest)
+        (err errUnexpectedByte bs)
+        (byteEq actual expected))
+    (readU8 bs))
+
+read2 = (bs : readBytes 2 bs)
+read4 = (bs : readBytes 4 bs)
+
+mapResult = (f result :
+  matchResult
+    (code rest : err code rest)
+    (value rest : ok (f value) rest)
+    result)
+
+bindResult = (result f :
+  matchResult
+    (code rest : err code rest)
+    (value rest : f value rest)
+    result)
+
+readU16BEBytes = (bs : read2 bs)
+readU32BEBytes = (bs : read4 bs)