All: split types into types, env, printer, core.

- types: low-level mapping to the implementation language.
- core: functions on types that are exposed directly to mal.
- printer: implementation called by pr-str, str, prn, println.
- env: the environment implementation

- Also, unindent all TCO while loops so that the diff of step4 and
  step5 are minimized.

1 files changed, 28 insertions, 0 deletions

diff --git a/python/env.py b/python/env.py
new file mode 100644
index 0000000..4cd8e05
--- /dev/null
+++ b/python/env.py
@@ -0,0 +1,28 @@
+# Environment
+
+class Env():
+    def __init__(self, outer=None, binds=None, exprs=None):
+        self.data = {}
+        self.outer = outer or None
+
+        if binds:
+            for i in range(len(binds)):
+                if binds[i] == "&":
+                    self.data[binds[i+1]] = exprs[i:]
+                    break
+                else:
+                    self.data[binds[i]] = exprs[i]
+
+    def find(self, key):
+        if key in self.data: return self
+        elif self.outer:     return self.outer.find(key)
+        else:                return None
+
+    def set(self, key, value):
+        self.data[key] = value
+        return value
+
+    def get(self, key):
+        env = self.find(key)
+        if not env: raise Exception("'" + key + "' not found")
+        return env.data[key]