Update boot.dst and lazyseq examples.

examples/lazyseqs.dst

@@ -17,7 +17,7 @@
 
 (defmacro delay 
  "Macro for lazy evaluation"
- [x] (tuple mem0 (tuple 'fn [] x)))
+ [& forms] (tuple mem0 (apply tuple (array-concat ['fn []] forms))))
 
 # Use tuples instead of structs to save memory
 (def HEAD :private 0)
@@ -32,6 +32,11 @@
  [h t]
  (delay (tuple h t)))
 
+(defn cons1
+ "Create a new sequence cons by prepending a value to the original sequence."
+ [h t]
+ (tuple h t))
+
 (defn empty? 
  "Check if a sequence is empty."
  [s]
@@ -47,17 +52,24 @@
  [s]
  (get (s) TAIL))
 
-(defn range 
+(defn range2 
  "Return a sequence of integers [start, end)."
  [start end]
  (if (< start end)
   (cons start (range (+ 1 start) end))
   empty-seq))
 
+(defn range
+ "Return a sequence of integers [0, end)."
+ [end]
+ (range2 0 end))
+
 (defn map
  "Return a sequence that is the result of apply f to each value in s."
  [f s]
- (if (s) (cons (f (head s)) (map f (tail s))) empty-seq))
+ (delay
+  (def x (s))
+  (if x (tuple (f (get x HEAD)) (map f (get x TAIL))))))
 
 (defn realize
  "Force evaluation of a lazy sequence."
@@ -71,7 +83,9 @@
 (defn drop 
  "Ignores the first n values of the sequence and returns the rest."
  [n s]
- (if (s) (if (zero? n) s (drop (- n 1) (tail s))) empty-seq))
+ (delay
+  (def x (s))
+  (if (s) (if (zero? n) s (drop (- n 1) (tail s))) empty-seq))
 
 (defn take
  "Returns at most the first n values of s."
@@ -80,3 +94,8 @@
   (cons (head s) (take (- n 1) (tail s)))
   empty-seq))
 
+(defn take-while
+ "Returns a sequence of values until the predicate is false."
+ [pred s]
+ (delay (if (s) )))
+

src/compiler/boot.dst

@@ -1,11 +1,6 @@
 # Bootstrap the dst environment
 # Copyright 2018 (C) Calvin Rose
 
-# Capture the current env
-(var *env*
- "A var that points to the current environment."
- _env)
-
 (def defn :macro
  "Define a function"
   (fn [name & more] 
@@ -82,16 +77,20 @@ are matched. If there are no matches, return nil."
        (aux (+ i 2))))))
   (aux 0))
 
-(defn doc
- "Shows documentation for the given symbol."
- [sym]
- (def x (get *env* sym))
+(defn doc*
+ [env sym]
+ (def x (get env sym))
  (if (not x)
   (print "symbol " x " not found.")
   (do
    (def d (get x 'doc))
    (print "\n" (if d d "no documentation found.") "\n"))))
 
+(defmacro doc
+ "Shows documentation for the given symbol."
+ [sym]
+ (tuple doc* '_env sym))
+
 (defmacro select
 "Select the body that equals the dispatch value. When pairs
 has an odd number of arguments, the last is the default expression.
@@ -141,13 +140,13 @@ If no match is found, returns nil"
   (def iters {
     :array array-iter
     :tuple array-iter
-    :struct (fn [x] x)})
+    :struct identity})
   (fn [x]
    (def makei (get iters (type x)))
    (if makei (makei x) (error "expected sequence")))))
 
-(defn range [top]
-  (var i 0)
+(defn range2 [bottom top]
+  (var i bottom)
   {
     :more (fn [] (< i top))
     :next (fn []
@@ -156,6 +155,8 @@ If no match is found, returns nil"
       ret) 
   })
 
+(defn range [top] (range2 0 top))
+
 (defn doiter [itr] 
  (def {:more more :next next} (iter itr))
  (while (more) (next)))
@@ -337,6 +338,7 @@ If no match is found, returns nil"
 (defn make-env [parent]
  (def parent (if parent parent _env))
  (def newenv (setproto @{} parent))
+ (put newenv '_env @{'value newenv})
  newenv)
 
 # Remove the reference to the default _env
@@ -401,10 +403,7 @@ onvalue."
   (if (= (fiber-status f) :error)
    (onerr "runtime" res)
    (onvalue res)))
- (def oldenv *env*)
- (varset! *env* env) 
  (foreach (val-stream chunks onerr) doone)
- (varset! *env* oldenv)
  env)))
 
 (def require (do
@@ -426,14 +425,17 @@ onvalue."
      (put loading path nil)
      newenv)))))
 
-(defn import [path & args]
- (def env (require path))
+(defn import* [env path & args]
+ (def newenv (require path))
  (def {
   :prefix prefix
   } (apply table args))
- (foreach (pairs env) (fn [[k v]]
+ (foreach (pairs newenv) (fn [[k v]]
   (when (not (get v :private))
-   (put *env* (symbol (if prefix prefix "") k) v)))))
+   (put env (symbol (if prefix prefix "") k) v)))))
+
+(defmacro import [path & args]
+ (apply tuple (array-concat [import* '_env path] args))) 
 
 (defn repl [getchunk]
  (def newenv (make-env))