Currying

currying/__init__.py

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+

currying/src/__init__.py

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+

currying/src/lib.py

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+# Curry a given function.
+# If the definition uses *args, specify the amount given in a specific case
+def curry(f: callable, arity=None):
+    if arity is None:
+        arity = f.__code__.co_argcount
+    elif arity < 0:
+        raise Exception("negative arity")
+    elif arity < f.__code__.co_argcount:
+        raise Exception("specified arity is lesser than required")
+
+    if arity == 0:
+        return lambda: f()
+
+    def inner(*args):
+        if len(args) >= arity:
+            return f(*args)
+
+        return lambda arg: inner(*args, arg)
+
+    return lambda arg: inner(arg)
+
+
+# Uncurry a curried function
+def uncurry(f: callable):
+    def inner(*args):
+        value = f
+
+        for arg in args:
+            try:
+                value = value(arg)
+            except Exception:
+                raise Exception("incorrect amount of arguments provided")
+
+        return value
+
+    return inner

currying/tests/__init__.py

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+

currying/tests/test.py

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+import pytest
+
+from ..src.lib import curry, uncurry
+
+
+def add_args(*args):
+    return sum(args)
+
+
+def add2(a, b):
+    return a + b
+
+
+def test_specified():
+    assert curry(add_args, 3)(1)(2)(3) == 6
+
+
+def test_negative():
+    with pytest.raises(Exception) as e:
+        curry(add2, -1)
+        assert e == "negative arity"
+
+
+def test_less():
+    with pytest.raises(Exception) as e:
+        curry(add2, 1)
+        assert e == "specified arity is lesser than required"
+
+
+def test_unspecified():
+    assert curry(add2)(1)(2) == 3
+
+
+def test_zero():
+    assert curry(add_args, 0)() == 0
+
+
+def test_uncurry():
+    assert uncurry(curry(add2))(1, 2) == 3
+
+
+def test_uncurry_incorrect():
+    with pytest.raises(Exception) as e:
+        uncurry(curry(add2))(1, 2, 3)
+        assert e == "incorrect amount of arguments provided"