1 files changed, 52 insertions, 0 deletions
diff --git a/nim/step2_eval.nim b/nim/step2_eval.nim
new file mode 100644
index 0000000..075b4ac
--- /dev/null
+++ b/nim/step2_eval.nim
@@ -0,0 +1,52 @@
+import rdstdin, tables, sequtils, types, reader, printer
+
+proc read(str: string): MalType = str.read_str
+
+proc eval(ast: MalType, env: Table[string, MalType]): MalType
+
+proc eval_ast(ast: MalType, env: Table[string, MalType]): MalType =
+  case ast.kind
+  of Symbol:
+    if not env.hasKey(ast.str):
+      raise newException(ValueError, "'" & ast.str & "' not found")
+    result = env[ast.str]
+  of List:
+    result = list ast.list.mapIt(MalType, it.eval(env))
+  of Vector:
+    result = vector ast.list.mapIt(MalType, it.eval(env))
+  of HashMap:
+    result = hash_map()
+    for k, v in ast.hash_map.pairs:
+      result.hash_map[k] = v.eval(env)
+  else:
+    result = ast
+
+proc eval(ast: MalType, env: Table[string, MalType]): MalType =
+  case ast.kind
+  of List:
+    let el = ast.eval_ast(env)
+    el.list[0].fun(el.list[1 .. -1])
+  else:
+    ast.eval_ast(env)
+
+proc print(exp: MalType): string = exp.pr_str
+
+template wrapNumberFun(op: expr): expr =
+  fun proc(xs: varargs[MalType]): MalType = number op(xs[0].number, xs[1].number)
+
+let repl_env = toTable({
+  "+": wrapNumberFun `+`,
+  "-": wrapNumberFun `-`,
+  "*": wrapNumberFun `*`,
+  "/": wrapNumberFun `div`,
+})
+
+proc rep(str: string): string =
+  str.read.eval(repl_env).print
+
+while true:
+  try:
+    let line = readLineFromStdin("user> ")
+    echo line.rep
+  except:
+    echo getCurrentExceptionMsg()