Merge pull request #240 from thomasmulvaney/env

Adds an evironment associative structure

Author: halgari

pixie/stdlib.pxi

@@ -2340,3 +2340,13 @@ Expands to calls to `extend-type`."
 (def *e)
 (defn -set-*e [e]
   (def *e e))
+
+(extend -str Environment
+        (fn [v]
+          (let [entry->str (map (fn [e] (vector (-repr (key e)) " " (-repr (val e)))))]
+            (apply str "#Environment{" (conj (transduce (comp entry->str (interpose [", "]) cat) conj v) "}")))))
+
+(extend -repr Environment
+        (fn [v]
+          (let [entry->str (map (fn [e] (vector (-repr (key e)) " " (-repr (val e)))))]
+            (apply str "#Environment{" (conj (transduce (comp entry->str (interpose [", "]) cat) conj v) "}")))))

pixie/vm/libs/env.py

@@ -0,0 +1,55 @@
+from pixie.vm.code import as_var
+from pixie.vm.object import Object, Type, runtime_error
+from pixie.vm.primitives import nil
+from pixie.vm.string import String
+import pixie.vm.stdlib as proto
+from  pixie.vm.code import extend, as_var
+import pixie.vm.rt as rt
+import os
+
+class Environment(Object):
+    _type = Type(u"pixie.stdlib.Environment")
+
+    def type(self):
+        return Environment._type
+
+    def val_at(self, key, not_found):
+        if not isinstance(key, String):
+            runtime_error(u"Environment variables are strings ")
+        key_str = str(rt.name(key))
+        try:
+            var = os.environ[key_str]
+            return rt.wrap(var)
+        except KeyError:
+            return not_found
+    
+    # TODO: Implement me.
+    # def dissoc(self):
+    # def asssoc(self):
+
+    def reduce_vars(self, f, init):
+        for k, v in os.environ.items():
+            init = f.invoke([init, rt.map_entry(rt.wrap(k), rt.wrap(v))])
+            if rt.reduced_QMARK_(init):
+                return init
+        return init
+
+ 
+@extend(proto._val_at, Environment)
+def _val_at(self, key, not_found):
+    assert isinstance(self, Environment)
+    v = self.val_at(key, not_found)
+    return v
+
+@extend(proto._reduce, Environment)
+def _reduce(self, f, init):
+    assert isinstance(self, Environment)
+    val = self.reduce_vars(f, init)
+    if rt.reduced_QMARK_(val):
+        return rt.deref(val)
+
+    return val
+
+@as_var("pixie.stdlib", "env")
+def _env():
+    return Environment()

pixie/vm/rt.py

@@ -65,6 +65,7 @@ def wrapper(*args):
     import pixie.vm.map_entry
     import pixie.vm.libs.platform
     import pixie.vm.libs.ffi
+    import pixie.vm.libs.env
     import pixie.vm.symbol
     import pixie.vm.libs.path
     import pixie.vm.libs.string

pixie/vm/stdlib.py

@@ -864,4 +864,3 @@ def _set_current_var_frames(self, frames):
        Sets the current var frames. Frames should be a cons list of hashmaps containing mappings of vars to dynamic
        values. Setting this value to anything but this data format will cause undefined errors."""
     code._dynamic_vars.set_current_frames(frames)
-