Data commit

Task/Middle-three-digits/Python/middle-three-digits-1.py

@@ -0,0 +1,35 @@
+>>> def middle_three_digits(i):
+	s = str(abs(i))
+	length = len(s)
+	assert length >= 3 and length % 2 == 1, "Need odd and >= 3 digits"
+	mid = length // 2
+	return s[mid-1:mid+2]
+
+>>> passing = [123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345]
+>>> failing = [1, 2, -1, -10, 2002, -2002, 0]
+>>> for x in passing + failing:
+	try:
+		answer = middle_three_digits(x)
+	except AssertionError as error:
+		answer = error
+	print("middle_three_digits(%s) returned: %r" % (x, answer))
+
+	
+middle_three_digits(123) returned: '123'
+middle_three_digits(12345) returned: '234'
+middle_three_digits(1234567) returned: '345'
+middle_three_digits(987654321) returned: '654'
+middle_three_digits(10001) returned: '000'
+middle_three_digits(-10001) returned: '000'
+middle_three_digits(-123) returned: '123'
+middle_three_digits(-100) returned: '100'
+middle_three_digits(100) returned: '100'
+middle_three_digits(-12345) returned: '234'
+middle_three_digits(1) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(2) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(-1) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(-10) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(2002) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(-2002) returned: AssertionError('Need odd and >= 3 digits',)
+middle_three_digits(0) returned: AssertionError('Need odd and >= 3 digits',)
+>>>

Task/Middle-three-digits/Python/middle-three-digits-2.py

@@ -0,0 +1,85 @@
+'''Middle 3 digits'''
+
+
+# mid3digits :: Int -> Either String String
+def mid3digits(n):
+    '''Either the middle three digits,
+       or an explanatory string.'''
+    m = abs(n)
+    s = str(m)
+    return Left('Less than 3 digits') if (100 > m) else (
+        Left('Even digit count') if even(len(s)) else Right(
+            s[(len(s) - 3) // 2:][0:3]
+        )
+    )
+
+
+# TEST ----------------------------------------------------
+def main():
+    '''Test'''
+
+    def bracketed(x):
+        return '(' + str(x) + ')'
+
+    print(
+        tabulated('Middle three digits, where defined:\n')(str)(
+            either(bracketed)(str)
+        )(mid3digits)([
+            123, 12345, 1234567, 987654321, 10001, -10001, -123,
+            -100, 100, -12345, 1, 2, -1, -10, 2002, -2002, 0
+        ])
+    )
+
+
+# GENERIC -------------------------------------------------
+
+# Left :: a -> Either a b
+def Left(x):
+    '''Constructor for an empty Either (option type) value
+       with an associated string.'''
+    return {'type': 'Either', 'Right': None, 'Left': x}
+
+
+# Right :: b -> Either a b
+def Right(x):
+    '''Constructor for a populated Either (option type) value'''
+    return {'type': 'Either', 'Left': None, 'Right': x}
+
+
+# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
+def compose(g):
+    '''Function composition.'''
+    return lambda f: lambda x: g(f(x))
+
+
+# either :: (a -> c) -> (b -> c) -> Either a b -> c
+def either(fl):
+    '''The application of fl to e if e is a Left value,
+       or the application of fr to e if e is a Right value.'''
+    return lambda fr: lambda e: fl(e['Left']) if (
+        None is e['Right']
+    ) else fr(e['Right'])
+
+
+# even :: Int -> Bool
+def even(x):
+    '''Is x even ?'''
+    return 0 == x % 2
+
+
+# tabulated :: String -> (b -> String) -> (a -> b) -> [a] -> String
+def tabulated(s):
+    '''Heading -> x display function -> fx display function ->
+                f -> value list -> tabular string.'''
+    def go(xShow, fxShow, f, xs):
+        w = max(map(compose(len)(str), xs))
+        return s + '\n' + '\n'.join(
+            xShow(x).rjust(w, ' ') + ' -> ' + fxShow(f(x)) for x in xs
+        )
+    return lambda xShow: lambda fxShow: lambda f: lambda xs: go(
+        xShow, fxShow, f, xs
+    )
+
+
+if __name__ == '__main__':
+    main()