Helpful library updates

lib/binary.tri

@@ -54,19 +54,65 @@ expectU8 = (expected bs :
         (byteEq? actual expected))
     (readU8 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)
-
 read2 = (bs : readBytes 2 bs)
 read4 = (bs : readBytes 4 bs)
 readU16BEBytes = (bs : read2 bs)
 readU32BEBytes = (bs : read4 bs)
+
+-- ---------------------------------------------------------------------------
+-- Parser combinators
+-- ---------------------------------------------------------------------------
+
+pureParser = value bs : ok value bs
+failParser = code bs : err code bs
+
+mapParser = f p bs : mapResult f (p bs)
+bindParser = p f bs : bindResult (p bs) f
+thenParser = p q bs : bindResult (p bs) (_ : q)
+
+orParser = (p q bs :
+  matchResult
+    (_ _ : q bs)
+    (value rest : ok value rest)
+    (p bs))
+
+readWhile_ = y (self pred bs acc :
+  matchResult
+    (code rest : ok (reverse acc) bs)
+    (value rest :
+      matchBool
+        (self pred rest (pair value acc))
+        (ok (reverse acc) (pair value rest))
+        (pred value))
+    (readU8 bs))
+
+readWhile = pred bs : readWhile_ pred bs t
+
+readUntil = pred : readWhile (x : not? (pred x))
+
+readRemaining = bs : ok bs t
+
+peekU8 = (bs :
+  matchResult
+    (code rest : err code bs)
+    (value rest : ok value bs)
+    (readU8 bs))
+
+eof? = (bs :
+  matchBool
+    (ok t bs)
+    (err errUnexpectedEof bs)
+    (emptyList? bs))
+
+expectAscii = expectBytes
+
+-- ---------------------------------------------------------------------------
+-- Endian / int conversion helpers
+-- ---------------------------------------------------------------------------
+
+u16BE = bytes : add (mul 256 (head bytes)) (head (tail bytes))
+
+u16LE = bytes : add (mul 256 (head (tail bytes))) (head bytes)
+
+readU16BE = bs : bindParser read2 (bytes rest : ok (u16BE bytes) rest) bs
+readU16LE = bs : bindParser read2 (bytes rest : ok (u16LE bytes) rest) bs