"unhashable type" is a beginner-unfriendly error message #132825
Description
Feature or enhancement
Proposal:
Every time I'm teaching dicts and sets to beginners, someone tries to use lists or other mutable data structures as dict keys or set members. The error message in that case is unhelpful, because it describes the problem in very technical terms (when you're just starting you have no idea what a hash function is). it could be changed to also add what operation is impossible as a result:
>>> s = set()
>>> s.add({'pages': 12, 'grade': 'A'})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: Cannot use 'dict' as a set element (unhashable type).
>>> d = {}
>>> l = [1, 2, 3]
>>> d[l] = 12
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: Cannot use 'list' as a dict key (unhashable type).That way, the problem is stated much more in terms of what the programmer is actually trying to do.
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response