Implement map

minitorch/operators.py

@@ -142,8 +142,11 @@ def map(fn: Callable[[float], float]) -> Callable[[Iterable[float]], Iterable[fl
          A function that takes a list, applies `fn` to each element, and returns a
          new list
     """
-    # TODO: Implement for Task 0.3.
-    raise NotImplementedError("Need to implement for Task 0.3")
+
+    def new_fn(ls: Iterable[float]) -> Iterable[float]:
+        return [fn(x) for x in ls]
+
+    return new_fn
 
 
 def negList(ls: Iterable[float]) -> Iterable[float]:

tests/test_operators.py

@@ -1,4 +1,4 @@
-from typing import Callable, List, Tuple
+from typing import Callable, List, Tuple, Iterable
 
 import pytest
 from hypothesis import given
@@ -15,6 +15,7 @@
     log_back,
     lt,
     max,
+    map,
     mul,
     neg,
     negList,
@@ -162,6 +163,22 @@ def test_other(a: float, b: float, c: float) -> None:
 # properties.
 
 
+@pytest.mark.task0_3
+@given(lists(small_floats, min_size=0, max_size=100), small_floats)
+def test_map(ls: Iterable[float], a: float) -> None:
+    def fn(x: float) -> float:
+        return x + a
+
+    def fn2(x: float) -> float:
+        return x * a
+
+    expected1 = [fn(x) for x in ls]
+    expected2 = [fn2(x) for x in ls]
+
+    assert expected1 == map(fn)(ls)
+    assert expected2 == map(fn2)(ls)
+
+
 @pytest.mark.task0_3
 @given(small_floats, small_floats, small_floats, small_floats)
 def test_zip_with(a: float, b: float, c: float, d: float) -> None: