remove redundant arity checks

1 files changed, 4 insertions, 19 deletions

diff --git a/interpreter.py b/interpreter.py
index f342caa..e8c0271 100644
--- a/interpreter.py
+++ b/interpreter.py
@@ -102,8 +102,6 @@ GLOBALS.register("and", Function(interpretAnd))
 
 def interpretEq(expr):
     # equal
-    if len(expr.args) != 2:
-        raise Exception("'eq?' needs two arguments")
     first = evaluate(expr.args[0])
     second = evaluate(expr.args[1])
     return first == second
@@ -111,8 +109,6 @@ def interpretEq(expr):
 GLOBALS.register("eq?", Function(interpretEq, 2))
 
 def interpretComparison(expr):
-    if len(expr.args) != 2:
-        raise Exception("comparisons have two operands")
     left = evaluate(expr.args[0])
     if type(left) not in (int, float):
         raise Exception("'left' must be a number")
@@ -155,8 +151,6 @@ GLOBALS.register("-", Function(interpretTerm))
 
 def interpretFactor(expr):
     if expr.symbol.name == "/":
-        if len(expr.args) != 2:
-            raise Exception("'/' requires two operands")
         num = evaluate(expr.args[0])
         if type(num) not in (int, float):
             raise Exception("numerator must be a number")
@@ -182,8 +176,6 @@ GLOBALS.register("*", Function(interpretFactor))
 GLOBALS.register("/", Function(interpretFactor, 2))
 
 def interpretNot(expr):
-    if len(expr.args) != 1:
-        raise Exception("'not' takes one operand")
     res = evaluate(expr.args[0])
     if res not in (True, False):
         raise Exception("'not' only works on booleans")
@@ -193,8 +185,6 @@ GLOBALS.register("not", Function(interpretNot, 1))
 
 def interpretIf(expr):
     # if cond t-branch [f-branch]
-    if len(expr.args) not in (2, 3):
-        raise Exception("too many or too few operands")
     cond = evaluate(expr.args[0])
     if cond not in (True, False):
         raise Exception("'if' condition must be boolean")
@@ -207,21 +197,16 @@ def interpretIf(expr):
 GLOBALS.register("if", Function(interpretIf, 2, 3))
 
 def interpretPrint(expr):
-    if len(expr.args) == 1:
-        ev = evaluate(expr.args[0])
-        if not isinstance(ev, str):
-            raise Exception("can only 'print' strings")
-        print(ev)
-    else:
-        raise Exception("'print' takes one argument")
+    ev = evaluate(expr.args[0])
+    if not isinstance(ev, str):
+        raise Exception("can only 'print' strings")
+    print(ev)
 
     return None  # print returns nothing
 
 GLOBALS.register("print", Function(interpretPrint, 1))
 
 def interpretDef(expr, env):
-    if len(expr.args) != 2:
-        raise Exception("'def' requires a name and an expression")
     if not isinstance(expr.args[0], Expr.Symbol):
         raise Exception("'def' requires a string literal as a name")
     name = expr.args[0].name  # NOTE: we are not evaluating the name!!