From db5564306399f0a3af97eb13808140542aa5b42c Mon Sep 17 00:00:00 2001
From: mryouse
Date: Tue, 10 May 2022 04:12:04 +0000
Subject: nested expressions!

---
 parser.py | 17 ++++++++++++-----
 runner.py |  6 ++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/parser.py b/parser.py
index 6360b62..97717bf 100644
--- a/parser.py
+++ b/parser.py
@@ -7,19 +7,26 @@ def peek(inp):
     return inp[0]
 
 def parse_expression(tkns):
-    # expressions MUST start with a symbol (for now?)
     symbol = None
     args = []
+    add_idx = 0
     for idx, t in enumerate(tkns):
-        #if isinstance(t, NebOpen):
+        # if we evaluated a nested expression, skip ahead
+        if add_idx > 0:
+            add_idx -= 1
+            continue
         if idx == 0:
             if not isinstance(t, NebSymbol):
                 raise Exception("expressions must start with a symbol")
             else:
                 symbol = t
         elif isinstance(t, NebClose):
-            return NebExpression(symbol, args), tkns[idx + 1:]
-        else:  # TODO nested expressions
+            return NebExpression(symbol, args), tkns[idx + 1:], idx + 1
+        # nested expressions
+        elif isinstance(t, NebOpen):
+            expr, remainder, add_idx = parse_expression(tkns[idx + 1:])
+            args.append(expr)
+        else:
             args.append(t)
             
     raise Exception("couldn't parse expression!")
@@ -29,7 +36,7 @@ def parse(tkns, parsed):
     if nxt is None:
         return parsed
     if isinstance(nxt, NebOpen):
-        expr, remainder = parse_expression(tkns[1:])
+        expr, remainder, _ = parse_expression(tkns[1:])
         parsed.append(expr)
         return parse(remainder, parsed)
     elif isinstance(nxt, NebLiteral):
diff --git a/runner.py b/runner.py
index 8e4f86d..0d8560e 100644
--- a/runner.py
+++ b/runner.py
@@ -23,6 +23,12 @@ def evaluate(items, pop):
         if not nxt.symbol.name in STD:
             raise Exception(f"no such symbol: {nxt.symbol.name}")
         this_func = STD[nxt.symbol.name]
+
+        # evaluate inner expressions
+        for idx, arg in enumerate(nxt.args):
+            if isinstance(arg, NebExpression):
+                nxt.args[idx] = evaluate([arg], pop)
+
         if nxt.maybe_sig() not in this_func:
             raise Exception(f"'{nxt.symbol.name}' called with unknown signature: '{nxt.maybe_sig()}'")
         ret = this_func[nxt.maybe_sig()].impl(*(nxt.args))
-- 
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