1 files changed, 61 insertions, 0 deletions
diff --git a/interpreter.py b/interpreter.py
index e888944..03b5c00 100644
--- a/interpreter.py
+++ b/interpreter.py
@@ -1,4 +1,5 @@
 from structs import Literal, Symbol, List
+from pathlib import Path
 
 class Function:
 
@@ -332,3 +333,63 @@ def interpretFunc(symbol, args, env):
 
 GLOBALS.register("func", Builtin(interpretFunc))
 
+# THINGS NEEDED FOR AOC
+#  - read the contents of a file
+def interpretReadLines(symbol, args, env):
+    target_file_name = evaluate(args[0], env)
+    target_file = Path(target_file_name).resolve()
+    if not target_file.exists():
+        raise Exception(f"no such file: {target_file}")
+    with open(target_file, "r") as fil:
+        data = fil.readlines()
+    out = List([Literal(d) for d in data]) # all lines are strings
+    return out
+
+GLOBALS.register("read-lines", Builtin(interpretReadLines, 1))
+
+#  - strip whitespace from string
+def interpretStrip(symbol, args, env):
+    out = evaluate(args[0], env)
+    return out.strip()
+
+GLOBALS.register("strip", Builtin(interpretStrip, 1))
+
+#  - string->int and string->float
+#  - split a string by a given field
+#  - get the length of a list
+#  - first/rest of list
+def interpretFirst(symbol, args, env):
+    ev = evaluate(args[0], env)
+    if not isinstance(ev, List):
+        raise Exception("'first' expects a List")
+    if len(ev.args) == 0:
+        raise Exception("List is empty")
+    return evaluate(ev.args[0], env)
+
+GLOBALS.register("first", Builtin(interpretFirst, 1))
+
+def interpretRest(symbol, args, env):
+    ev = evaluate(args[0], env)
+    if not isinstance(ev, List):
+        raise Exception("'rest' expects a List")
+    return List(ev.args[1:]) # we don't evaluate the remainder of the list
+
+GLOBALS.register("rest", Builtin(interpretRest, 1))
+
+#  - iterate over list
+#  - map
+def interpretMap(symbol, args, env):
+    # TODO: to support lambdas, we can't assume the func is defined
+    func = args[0]
+    if not isinstance(func, Symbol):
+        raise Exception("'map' takes a function as its first argument")
+    lst = evaluate(args[1], env)
+    if not isinstance(lst, List):
+        raise Exception("'map' takes a List as its second argument")
+    out = []
+    for arg in lst.args:
+        ev = evaluate(List([func, arg]), env)
+        out.append(ev)
+    return List(out)
+
+GLOBALS.register("map", Builtin(interpretMap, 2))