We have the beginning of a stdlib and can parse keyword and rest args

2018-10-20 23:27:51 +02:00
parent 42d64a0743
commit 488b47f08f
10 changed files with 306 additions and 21 deletions
@@ -0,0 +1,73 @@
+(define nil ())
+
+(define nil?
+  (lambda (x)
+    "Checks if the argument is nil."
+    (= x nil)))
+
+(define append
+  (lambda (obj sequence)
+    (if (nil? sequence)
+        (list obj)
+      (if (nil? (rest sequence))
+          ))))
+
+(define range
+  (lambda (:keys from :defaults-to 0 to)
+    "Returns a sequence of numbers starting with the number
+defined by the key 'from' and ends with the number defined in
+'to'."
+    (if (<= from to)
+        (pair from (range :from (+ 1 from) :to to))
+      nil)))
+
+(define map
+  (lambda (function sequence)
+    "Takes a sequence and a function as arguments and returns a
+new sequence which contains the results of using the first
+sequences elemens as argument to that function."
+    (if (nil? sequence)
+        sequence
+      (pair (function (first sequence))
+            (map (rest sequence) function)))))
+
+(define reduce
+  (lambda (function sequence)
+    "Takes a sequence and a function as arguments and applies the
+function to the argument sequence. This only works correctly if the
+given function accepts a variable amount of parameters. If your
+funciton is limited to two arguments, use `reduce-binary' instead."
+    (eval (pair function sequence))))
+
+(define reduce-binary
+  (lambda (function sequence)
+    "Takes a sequence and a function as arguments and applies the
+function to the argument sequence. reduce-binary applies the
+arguments `pair-wise' which means it works with binary functions
+as compared to `reduce'."
+    (if (nil? (rest sequence))
+        (first sequence)
+      (function (first sequence)
+                (reduce-binary (rest sequence) function)))))
+
+(define filter
+  (lambda (function sequence)
+    (if (nil? sequence)
+        nil
+      (if (function (first sequence))
+          (pair (first sequence)
+                (filter (rest sequence) function))
+        (filter (rest sequence) function)))))
+
+(define printf
+  (lambda (:keys sep :defaults-to " " end :defaults-to "\n" :rest args)
+    (if (and (nil? (first args)) (nil? (rest args)))
+        (print end)
+      (prog
+       (print (first args))
+       (if (not (nil? (rest args)))
+           (print sep))
+       ;; TODO(Felix): later we should use `extend' here:
+       ;; (eval (extend (quote (printf :sep sep :end end)) (rest args)))
+       (eval (pair printf (pair :sep (pair sep (pair :end (pair end (rest args)))))))
+       nil))))