Some refactoring.

1 files changed, 11 insertions, 9 deletions

diff --git a/stdlib/source/lux/data/text/lexer.lux b/stdlib/source/lux/data/text/lexer.lux
index 21aba8360..45a88bdf3 100644
--- a/stdlib/source/lux/data/text/lexer.lux
+++ b/stdlib/source/lux/data/text/lexer.lux
@@ -2,11 +2,13 @@
   [lux (#- or and not)
    [control
     [monad (#+ do Monad)]
-    ["p" parser]]
+    ["p" parser]
+    ["ex" exception (#+ exception:)]]
    [data
     ["." product]
     ["." maybe]
     ["e" error]
+    [number ("nat/." Codec<Text,Nat>)]
     [collection
      ["." list ("list/." Fold<List>)]]]
    [macro
@@ -24,15 +26,16 @@
   {#basis Offset
    #distance Offset})
 
+(def: cannot-lex-error Text "Cannot lex from empty text.")
+
 (def: (remaining offset tape)
   (-> Offset Text Text)
   (|> tape (//.split offset) maybe.assume product.right))
 
-(def: cannot-lex-error Text "Cannot lex from empty text.")
-
-(def: (unconsumed-input-error offset tape)
-  (-> Offset Text Text)
-  ($_ text/compose "Unconsumed input: " (remaining offset tape)))
+(exception: #export (unconsumed-input {offset Offset} {tape Text})
+  (ex.report ["Offset" (nat/encode offset)]
+             ["Input size" (nat/encode (//.size tape))]
+             ["Remaining input" (remaining offset tape)]))
 
 (def: #export (run input lexer)
   (All [a] (-> Text (Lexer a) (e.Error a)))
@@ -43,8 +46,7 @@
     (#e.Success [[end-offset _] output])
     (if (n/= end-offset (//.size input))
       (#e.Success output)
-      (#e.Error (unconsumed-input-error end-offset input)))
-    ))
+      (ex.throw unconsumed-input [end-offset input]))))
 
 (def: #export offset
   (Lexer Offset)
@@ -130,7 +132,7 @@
   (function (_ (^@ input [offset tape]))
     (if (n/= offset (//.size tape))
       (#e.Success [input []])
-      (#e.Error (unconsumed-input-error offset tape)))))
+      (ex.throw unconsumed-input [offset tape]))))
 
 (def: #export end?
   {#.doc "Ask if the lexer's input is empty."}