Add python.2 implementation

[jackhill/mal.git] / python.2 / step1_read_print.py

diff --git a/python.2/step1_read_print.py b/python.2/step1_read_print.py
new file mode 100644 (file)
index 0000000..1913c14
--- /dev/null
+++ b/python.2/step1_read_print.py
@@ -0,0 +1,38 @@
+import readline
+
+import reader
+from mal_types import MalExpression, MalSyntaxException
+
+
+def READ(x: str) -> MalExpression:
+    return reader.read(x)
+
+
+def EVAL(x: MalExpression) -> MalExpression:
+    return x
+
+
+def PRINT(x: MalExpression) -> str:
+    return str(x)
+
+
+def rep(x: str) -> str:
+    try:
+        return PRINT(EVAL(READ(x)))
+    except BaseException:
+        return "Expression is invalid or unbalanced: " + x
+
+
+if __name__ == "__main__":
+    # repl loop
+    eof: bool = False
+    while not eof:
+        try:
+            line = input("user> ")
+            readline.add_history(line)
+            try:
+                print(rep(line))
+            except MalSyntaxException as e:
+                print("ERROR: invalid syntax: " + str(e))
+        except EOFError:
+            eof = True