diff --git a/boolean_eval.py b/boolean_eval.py
new file mode 100644
index 0000000..fbbe51e
--- /dev/null
+++ b/boolean_eval.py
@@ -0,0 +1,66 @@
+# TODO: figure out how to deduplicate this with robustness
+# - Abstract as working on distributive lattice
+
+from functools import singledispatch
+import operator as op
+
+from lenses import lens
+
+import stl.ast
+
+@singledispatch
+def pointwise_sat(stl):
+    raise NotImplementedError
+
+
+@pointwise_sat.register(stl.Or)
+def _(stl):
+    return lambda x, t: any(pointwise_sat(arg)(x, t) for arg in stl.args)
+
+
+@pointwise_sat.register(stl.And)
+def _(stl):
+    return lambda x, t: all(pointwise_sat(arg)(x, t) for arg in stl.args)
+
+
+@pointwise_sat.register(stl.F)
+def _(stl):
+    lo, hi = stl.interval
+    return lambda x, t: any((pointwise_sat(stl.arg)(x, t + t2) 
+                             for t2 in x[lo:hi].index))
+
+
+@pointwise_sat.register(stl.G)
+def _(stl):
+    lo, hi = stl.interval
+    return lambda x, t: all((pointwise_sat(stl.arg)(x, t + t2) 
+                             for t2 in x[lo:hi].index))
+
+
+@pointwise_sat.register(stl.Neg)
+def _(stl):
+    return lambda x, t: not pointwise_sat(arg)(x, t)
+
+
+op_lookup = {
+    ">": op.gt,
+    ">=": op.ge,
+    "<": op.lt,
+    "<=": op.le,
+    "=": op.eq,
+}
+
+
+@pointwise_sat.register(stl.LinEq)
+def _(stl):
+    op = op_lookup[stl.op]
+    return lambda x, t: op(eval_terms(stl, x, t), stl.const)
+
+
+def eval_terms(lineq, x, t):
+    psi = lens(lineq).terms.each_().modify(eval_term(x, t))
+    return sum(psi.terms)
+
+
+def eval_term(x, t):
+    return lambda term: term.coeff*x[term.id.name][t]
diff --git a/test_boolean_eval.py b/test_boolean_eval.py
new file mode 100644
index 0000000..de5cbbe
--- /dev/null
+++ b/test_boolean_eval.py
@@ -0,0 +1,22 @@
+import stl
+import stl.boolean_eval
+import pandas as pd
+from nose2.tools import params
+import unittest
+from sympy import Symbol
+
+ex1 = ("2*A > 3", False)
+ex2 = ("F[0, 1](2*A > 3)", True)
+ex3 = ("F[1, 0](2*A > 3)", False)
+ex4 = ("G[1, 0](2*A > 3)", True)
+ex5 = ("(A < 0)", False)
+ex6 = ("G[0, 0.1](A < 0)", False)
+x = pd.DataFrame([[1,2], [1,4], [4,2]], index=[0,0.1,0.2], 
+                 columns=["A", "B"])
+
+class TestSTLRobustness(unittest.TestCase):
+    @params(ex1, ex2, ex3, ex4, ex5, ex6)
+    def test_stl(self, phi_str, r):
+        phi = stl.parse(phi_str)
+        stl_eval = stl.boolean_eval.pointwise_sat(phi)
+        self.assertEqual(stl_eval(x, 0), r)