From 5f0bd1e0829339fa0c0dcabd9fc14176eac56e99 Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Wed, 14 Mar 2018 21:46:56 -0400
Subject: [PATCH] Update code.

---
 examples/3sum.dst     | 14 ++++++++++++++
 src/compiler/boot.dst | 42 ++++++++++++++++++++++++++++++++----------
 src/core/struct.c     |  9 ++++-----
 3 files changed, 50 insertions(+), 15 deletions(-)
 create mode 100644 examples/3sum.dst

diff --git a/examples/3sum.dst b/examples/3sum.dst
new file mode 100644
index 00000000..2cc75a6f
--- /dev/null
+++ b/examples/3sum.dst
@@ -0,0 +1,14 @@
+(defn sum3
+ "Solve the 3SUM problem O(n^2) time."
+ [s]
+ (def tab @{})
+ (def solutions [])
+ (def len (length s))
+ (for [k 0 len]
+  (put tab (get s k) k))
+ (for [i 0 len]
+  (for [j 0 len]
+   (def k (get tab (- 0 (get s i) (get s j))))
+   (when (and k (not= k i) (not= k j) (not= i j))
+    (array-push solutions [i j k]))))
+ solutions)
diff --git a/src/compiler/boot.dst b/src/compiler/boot.dst
index 4fbaf971..43f47c31 100644
--- a/src/compiler/boot.dst
+++ b/src/compiler/boot.dst
@@ -32,6 +32,14 @@
  (apply tuple (array-concat
   ['defn name :private] more)))
 
+(defn even? [x] (== 0 (% x 2)))
+(defn odd? [x] (== 1 (% x 2)))
+(defn nil? [x] (= x nil))
+(defn zero? [x] (== x 0))
+(defn one? [x] (== x 1))
+(defn inc [x] (+ x 1))
+(defn dec [x] (- x 1))
+
 (defmacro comment
  "Ignores the body of the comment."
  [])
@@ -83,8 +91,19 @@ If no match is found, returns nil"
    (tuple 'def sym dispatch)
    (aux 0)))
 
-(defmacro or [x y] (tuple 'if x true y))
-(defmacro and [x y] (tuple 'if x y false))
+(defmacro and [& forms] 
+ (def len (length forms))
+ (if (= len 0) true ((fn aux [i]
+  (cond
+   (>= (inc i) len) (get forms i)
+   (tuple 'if (get forms i) (aux (inc i)) false))) 0)))
+
+(defmacro or [& forms] 
+ (def len (length forms))
+ (if (= len 0) false ((fn aux [i]
+  (cond
+   (>= (inc i) len) (get forms i)
+   (tuple 'if (get forms i) true (aux (inc i))))) 0)))
 
 (defn identity 
  "A function that returns its first argument."
@@ -136,6 +155,12 @@ If no match is found, returns nil"
  (def {:more more :next next} (seq s))
  (while (more) (f (next))))
 
+(defn seq-array [s] 
+ (def {:more more :next next} (seq s))
+ (def a [])
+ (while (more) (array-push a (next)))
+ a)
+
 (defn map [f s]
  (def {:more more :next next} (seq s))
  {:more more :next (fn [] (f (next)))})
@@ -164,14 +189,6 @@ If no match is found, returns nil"
  (defn nmore [] (when isnew (varset! isnew false) (nnext)) alive)
  {:more nmore :next nnext})
 
-(defn even? [x] (== 0 (% x 2)))
-(defn odd? [x] (== 1 (% x 2)))
-(defn nil? [x] (= x nil))
-(defn zero? [x] (== x 0))
-(defn one? [x] (== x 1))
-(defn inc [x] (+ x 1))
-(defn dec [x] (- x 1))
-
 (defmacro let [bindings & body]
   (def head (ast-unwrap1 bindings))
   (when (odd? (length head)) (error "expected even number of bindings to let"))
@@ -303,6 +320,11 @@ If no match is found, returns nil"
   (fn [x] (print (pp1 @{} @"" x)))))
 # End pretty printer
 
+(defn unique [s]
+  (def tab @{})
+  (domap (fn [x] (put tab x true)) s)
+  (keys tab))
+
 (defn make-env [parent]
  (def parent (if parent parent _env))
  (def newenv (setproto @{} parent))
diff --git a/src/core/struct.c b/src/core/struct.c
index c6955ded..9ab9a64a 100644
--- a/src/core/struct.c
+++ b/src/core/struct.c
@@ -61,11 +61,10 @@ const DstKV *dst_struct_find(const DstKV *st, Dst key) {
  * Nil keys and values are ignored, extra keys are ignore, and duplicate keys are
  * ignored. 
  *
- * Much of this complexity is in the robinhood hashing scheme, an
- * attempt to make structs that are created with arguments in a different
- * order to have the same internal representation. If this turns out to be
- * incorrect or too complicated, another scheme that would definitely work
- * is inserting all keys in sorted order with any deterministic hashing scheme. */
+ * Runs will be in sorted order, as the collisions resolver essentially
+ * preforms an in-place insertion sort. This ensures the internal structure of the
+ * hash map is independant of insertion order.
+ */
 void dst_struct_put(DstKV *st, Dst key, Dst value) {
     int32_t cap = dst_struct_capacity(st);
     int32_t hash = dst_hash(key);