diff --git a/interp.py b/interp.py
new file mode 100644
index 0000000..31ff90b
--- /dev/null
+++ b/interp.py
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: MIT
+# Copyright 2021 Jookia <contact@jookia.org>
+
+import parse
+
+def text_create(value):
+    return ("text", value)
+def text_value(object):
+    return object[1]
+def text_dispatch(object, verb, args):
+    value = text_value(object)
+    if verb == "Append":
+        appendix = text_value(args[0])
+        return text_create(value + " " + appendix)
+    return None
+
+def module_create(verbs):
+    return ("module", verbs)
+def module_dispatch(object, verb, args):
+    (type, functions) = object
+    return functions[verb](object, args)
+
+def do_system_print(subject, args):
+    print(text_value(args[0]))
+    return None
+def do_system_read(subject, args):
+    return text_create(input())
+system_module = module_create({
+    "Print": do_system_print,
+    "Read": do_system_read,
+})
+
+def resolve_value(env, value):
+    if value.__class__ == parse.Reference:
+        return env[value.value]
+    elif value.__class__ == parse.Text:
+        return text_create(value.value)
+    else:
+        print("Unimplemented value: %s" % (value))
+
+def run_statement(env, ast):
+    subject = resolve_value(env, ast.subject)
+    if ast.verb == None:
+        return subject
+    args = []
+    for arg in ast.arguments:
+        args.append(resolve_value(env, arg))
+    if subject[0] == "text":
+        return text_dispatch(subject, ast.verb, args)
+    elif subject[0] == "module":
+        return module_dispatch(subject, ast.verb, args)
+    return None
+
+def run_set(env, ast):
+    env[ast.subject] = run_statement(env, ast.statement)
+    return env[ast.subject]
+
+def run_if(env, ast):
+    print("Unimplemented if")
+    return None
+
+def run_command(env, ast):
+    if ast.__class__ == parse.Statement:
+        return run_statement(env, ast)
+    elif ast.__class__ == parse.Set:
+        return run_set(env, ast)
+    elif ast.__class__ == parse.Conditional:
+        return run_if(env, ast)
+    else:
+        print("Unknown command %s" % (ast))
+        return None
diff --git a/main.py b/main.py
index 2110050..98c776d 100755
--- a/main.py
+++ b/main.py
@@ -4,73 +4,7 @@
 
 import log
 import parse
-
-def text_create(value):
-    return ("text", value)
-def text_value(object):
-    return object[1]
-def text_dispatch(object, verb, args):
-    value = text_value(object)
-    if verb == "Append":
-        appendix = text_value(args[0])
-        return text_create(value + " " + appendix)
-    return None
-
-def module_create(verbs):
-    return ("module", verbs)
-def module_dispatch(object, verb, args):
-    (type, functions) = object
-    return functions[verb](object, args)
-
-def do_system_print(subject, args):
-    print(text_value(args[0]))
-    return None
-def do_system_read(subject, args):
-    return text_create(input())
-system_module = module_create({
-    "Print": do_system_print,
-    "Read": do_system_read,
-})
-
-def resolve_value(env, value):
-    if value.__class__ == parse.Reference:
-        return env[value.value]
-    elif value.__class__ == parse.Text:
-        return text_create(value.value)
-    else:
-        print("Unimplemented value: %s" % (value))
-
-def run_statement(env, ast):
-    subject = resolve_value(env, ast.subject)
-    if ast.verb == None:
-        return subject
-    args = []
-    for arg in ast.arguments:
-        args.append(resolve_value(env, arg))
-    if subject[0] == "text":
-        return text_dispatch(subject, ast.verb, args)
-    elif subject[0] == "module":
-        return module_dispatch(subject, ast.verb, args)
-    return None
-
-def run_set(env, ast):
-    env[ast.subject] = run_statement(env, ast.statement)
-    return env[ast.subject]
-
-def run_if(env, ast):
-    print("Unimplemented if")
-    return None
-
-def run_command(env, ast):
-    if ast.__class__ == parse.Statement:
-        return run_statement(env, ast)
-    elif ast.__class__ == parse.Set:
-        return run_set(env, ast)
-    elif ast.__class__ == parse.Conditional:
-        return run_if(env, ast)
-    else:
-        print("Unknown command %s" % (ast))
-        return None
+import interp
 
 def main(args):
     if len(args) != 2:
@@ -81,10 +15,10 @@
     if not ast:
         return 1
     env = {
-        "System": system_module,
+        "System": interp.system_module,
     }
     for command in ast:
-        run_command(env, command)
+        interp.run_command(env, command)
     return 0
 
 if __name__ == "__main__":