From df44c8979b90ae1db13ca11eefef16ba2dc5b0f1 Mon Sep 17 00:00:00 2001
From: Jay McCarthy <jay.mccarthy@gmail.com>
Date: Wed, 7 Oct 2015 11:04:11 -0400
Subject: [PATCH] little explanation

---
 remix/tests/simple.rkt | 61 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 50 insertions(+), 11 deletions(-)

diff --git a/remix/tests/simple.rkt b/remix/tests/simple.rkt
index 456729b..a9da67c 100644
--- a/remix/tests/simple.rkt
+++ b/remix/tests/simple.rkt
@@ -2,6 +2,12 @@
 (require remix/stx0
          remix/num/gen0)
 
+;; define is replaced with def
+(def z 42)
+(module+ test
+  z)
+
+;; when def has more forms than one, they are put inside of a block
 (def x
   (def a 40)
   (def b 2)
@@ -9,22 +15,35 @@
 (module+ test
   x)
 
+;; but of course def supports function definitions. [] is NOT the same
+;; as () and defaults to expanding to a block definition
 (def (f x y)
-  (+ [(def z (+ x x)) z] y))
+  (+ [(def z (+ x x))
+      z]
+     y))
 (module+ test
   (f x x))
 
+;; cond requires []s for the question-answer pairs. It uses this to
+;; make any code in between clauses go in between the `if`s that pop
+;; out of the cond macro. finally, cond REQUIRES a #:else clause.
 (def (g x)
   (cond
     [(< x 100) "100"]
     (def z (/ x 2))
     [(< z 100) "div 100"]
-    [#:else "other"]))
+    [#:else z]))
 (module+ test
   (g 50)
   (g 199)
   (g 200))
 
+;; the @ reader is always on. One fun thing about this is that you can
+;; make non-() macros. I wrote a little helper function to turn the
+;; string arguments that @{} produces into a string port that has
+;; accurate source location information for the original file. datalog
+;; uses this to make all the source locations correct, so errors in
+;; datalog will give accurate source locations.
 (require remix/datalog0)
 (def graph (make-theory))
 @datalog[graph]{
@@ -34,26 +53,26 @@
  path(X, Y)?
 }
 
+;; {} is also not (), but is an infix macro
 (def v7
   {3 + 4})
 (module+ test
   v7)
 
+;; {} use C's precedence and considers the things you expect to be
+;; operators
 (def v-26
   {2 * 3 - 48 / 4 - 4 * 5})
 (module+ test
   v-26)
 
-(def v15
-  {v7 * 2 + 1})
+;; if a symbol contains no alphabetic or numeric characters, then it
+;; is considered an operator. This means you can automatically use
+;; stuff like & and →, but you won't confuse it with symbols like z
+(def v85
+  {z * 2 + 1})
 (module+ test
-  v15)
-
-(def v14
-  (def (f x y) (+ x y))
-  {v7 ,f v7})
-(module+ test
-  v14)
+  v85)
 
 (def v1
   (def & bitwise-and)
@@ -61,6 +80,26 @@
 (module+ test
   v1)
 
+(def v56
+  (def (→ x y) (+ (* x x) y))
+  {v7 → v7})
+(module+ test
+  v56)
+
+;; However, if you use , then you can force anything to be a binary
+;; operator and force something that would have been a binary operator
+;; into an argument.
+(def v14
+  (def (f x y) (+ x y))
+  {v7 ,f v7})
+(module+ test
+  v14)
+
+(def v14b
+  {v7 ,(λ (x y) (+ x y)) v7})
+(module+ test
+  v14b)
+
 (def v9
   (def & 2)
   {v7 + ,&})