From c17932571945021ddc57794609add1920f78636e Mon Sep 17 00:00:00 2001
From: Scott Richmond <s.richmond@utoronto.ca>
Date: Thu, 1 Jun 2023 13:11:06 -0600
Subject: [PATCH] Improve prelude

---
 src/ludus/interpreter.clj |  4 +++-
 src/ludus/prelude.clj     | 31 ++++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/ludus/interpreter.clj b/src/ludus/interpreter.clj
index 4bca9da..cf2ac8c 100644
--- a/src/ludus/interpreter.clj
+++ b/src/ludus/interpreter.clj
@@ -963,7 +963,9 @@
 
 (do
   (def source "
-    
+    let xs = [1, 2, 3]
+    let ys = #{:a 1, :b 2}
+    get (:c, ys)
       ")
 
   (println "")
diff --git a/src/ludus/prelude.clj b/src/ludus/prelude.clj
index bf10de1..b21d07f 100644
--- a/src/ludus/prelude.clj
+++ b/src/ludus/prelude.clj
@@ -92,12 +92,36 @@
 
 (def get- {:name "get"
            ::data/type ::data/clj
-           :body get})
+           :body (fn 
+                   ([key, map]
+                    (if (map? map)
+                      (get map key)
+                      nil))
+                   ([key, map, default]
+                    (if (map? map)
+                      (get map key default)
+                      default)))})
 
 (def draw {:name "draw"
            ::data/type ::data/clj
            :body d/ludus-draw})
 
+(def first- {:name "first"
+             ::data/type ::data/clj
+             :body (fn [v] (second v))})
+
+(def rest- {:name "rest"
+            ::data/type ::data/clj
+            :body (fn [v]
+                    (into [::data/list] (nthrest v 2)))})
+
+(def nth- {:name "nth"
+           ::data/type ::data/clj
+           :body (fn [i, xs]
+                   (if (contains? xs (inc i))
+                     (nth xs (inc i))
+                     nil))})
+
 (defn get-type [value]
   (let [t (type value)]
     (cond
@@ -149,8 +173,6 @@
 
 (def prelude {
               "id" id
-              "foo" :foo
-              "bar" :bar
               "eq" eq
               "add" add
               "print" print-
@@ -172,4 +194,7 @@
               "draw" draw
               "type" type-
               "clj" clj
+              "first" first-
+              "rest" rest-
+              "nth" nth-
               })
\ No newline at end of file