I've just stumbled about some unexpected behavior in Python in the below code snippet
b = False
func_1 = lambda x,y:set([x]) == y if b else lambda x,y: x in y
func_2 = None
if not b:
func_2 = lambda x,y : x in y
else:
func_2 = lambda x,y:set([x]) == y
print(func_1("Hello", set(["Hello", "World"])))
print(func_2("Hello", set(["Hello", "World"])))
The output is
<function <lambda>.<locals>.<lambda> at 0x7f7e5eeed048>
True
However, when adding brackets around the lambdas everything works as expected:
func_1 = (lambda x,y:set([x]) == y) if b else (lambda x,y: x in y)
# ...
The output then is
True
True
Why do I need those brackets? I thought the initial expression was equivalent to the long if-else construct.
It's just standard precedence rules. Your first expression is being parsed as:
lambda x,y:set([x]) == (y if b else lambda x,y: x in y)
So you need to add the parentheses to create the correct precedence.
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