feat: tokenizer accepts braces, line terminator, and equal sign

samples/saccharine.txt

@@ -1,9 +1,16 @@
-0 := \f x.x
-(inc n) := \f x.(f (n f x))
-(add n m) := (m inc n)
-(mult n m) := (m (n f))
-(exp m n) := (m n)
+(true x y) := x
+(false x y) := y
 
-# This is the final output.
-5 := (inc (inc (inc (inc (inc 0)))))
-(exp 5 5)
+(pair a b) := \c.(c a b)
+(left p) := (p true)
+(false p) := (p false)
+
+zero 0 1 x = x
+
+inc n := \0 1 x.{
+  initial := (pair true x)
+  (on_zero p) := (pair false ((left p 1 0) (right p)))
+  (on_one p) := (pair (left p) (1 (right p)))
+  
+  (n on_zero on_one initial)
+}