Implement #9, rlwrap functionality.

requirements.txt

@@ -1,4 +1,5 @@
 lark == 1.1.2
+prompt_toolkit == 3.0.30
 pycodestyle == 2.5.0
 pytest
 versioneer == 0.22

setup.py

@@ -28,7 +28,8 @@
  ],
  },
  install_requires=[
- 'lark == 1.1.2'
+ 'lark == 1.1.2',
+ 'prompt_toolkit == 3.0.30',
  ],
  classifiers=[
  "Development Status :: 3 - Alpha",

smallscheme/main.py

@@ -2,7 +2,8 @@
 
 import argparse
 from smallscheme.env import Env
-from smallscheme.scheme import evalu, repl, parse_str
+from smallscheme.scheme import evalu, parse_str
+from smallscheme.repl import repl
 
 def run_file(filename):
  env = Env()

smallscheme/repl.py

@@ -0,0 +1,30 @@
+# prompt_toolkit setup example taken from
+# https://stackoverflow.com/questions/59627995:
+from prompt_toolkit import prompt
+from prompt_toolkit import PromptSession
+from prompt_toolkit.history import FileHistory
+from os.path import expanduser
+
+from smallscheme.env import Env
+from smallscheme.scheme import parse_str, evalu, printable_value
+
+
+def repl():
+ session = PromptSession(history=FileHistory(
+ expanduser('~/.smallscheme_history')))
+
+ env = Env()
+ while True:
+ try:
+ x = session.prompt("scheme> ").strip()
+ except EOFError:
+ print()
+ break
+ if x:
+ try:
+ for parsed in parse_str(x):
+ pv = printable_value(evalu(parsed, env))
+ if pv:
+ print(pv)
+ except Exception as e:
+ print(e)

smallscheme/scheme.py

@@ -131,26 +131,3 @@ def evalu(expr, env):
  if typeof(expr) == 'list':
  return eval_list(expr, env)
  raise Exception('evaluation error: "%s"' % str(expr))
-
-def inp():
- if sys.version_info > (2, 9):
- return input("scheme> ")
- else:
- return raw_input("scheme> ")
-
-def repl():
- env = Env()
- while True:
- try:
- x = inp().strip()
- except EOFError:
- print()
- break
- if x:
- try:
- for parsed in parse_str(x):
- pv = printable_value(evalu(parsed, env))
- if pv:
- print(pv)
- except Exception as e:
- print(e)