@Jose Thanks for the quick reply! I agree that this would provide a better
experience for Elixir. I'd be happy to contribute, but I'm very new to the
language. I may be able to do it with some hand-holding if you're up for it.
@Dmitry I disagree—I don't think this error message is clear.
String.replace/4 is calling Keyword.get/3 somewhere under the hood, and
that's where the error message is being thrown. As someone who's new to the
language, it's hard for me to tell what I did wrong when calling the method.
For context with another language, if I call "1234".gsub(:nope, "banana")
in Ruby, I get this error:
Traceback (most recent call last):
1: from test.rb:1:in `<main>'
test.rb:1:in `gsub': wrong argument type Symbol (expected Regexp)
(TypeError)
In Python, "1234".replace(1234, "banana", 1) produces this:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: replace() argument 1 must be str, not int
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: replace() argument 1 must be str, not int
On Sunday, September 15, 2019 at 4:03:04 PM UTC-7, Dmitry Belyaev wrote:
>
> The error message is clear:
> BracketPush.check_brackets makes a call to
> https://hexdocs.pm/elixir/String.html#replace/4 and passes empty string
> "" as the last argument instead of a list.
>
> In dynamically typed languages we expect the caller to pass the correct
> data for the function to behave as documented. Imagine every function
> typechecked every argument to the deepest primitive types - the code would
> become an incomprehensible mess and performance would be terrible wth every
> function type checking the data in runtime which was already typechecked
> one level higher.
>
> On 16 September 2019 7:50:56 am AEST, Landon Schropp <[email protected]
> <javascript:>> wrote:
>>
>> Hello!
>>
>> I'm new to Elixir development, so I'm approaching the language with fresh
>> eyes. One of the issues I've run into is difficulty understand the error
>> messages from the standard library. For example, today I ran this code:
>>
>> string
>> |> String.replace(string, ~r/[^\[\](){}]/, "")
>> |> IO.inspect(label: "\n")
>> |> String.codepoints
>> |> check_brackets([])
>>
>> When I run this code through one of my test cases, I get the following
>> error:
>>
>> 1) test math expression (BracketPushTest)
>> test/bracket_push_test.exs:52
>> ** (FunctionClauseError) no function clause matching in Keyword.get/
>> 3
>> The following arguments were given to Keyword.get/3:
>>
>>
>> # 1
>>
>> ""
>>
>>
>> # 2
>> :insert_replaced
>>
>>
>> # 3
>> nil
>>
>>
>> Attempted function clauses (showing 1 out of 1):
>>
>>
>> def get(keywords, key, default) when is_list(keywords) and
>> is_atom(key)
>>
>>
>> code: assert BracketPush.check_brackets("(((185 + 223.85) * 15) -
>> 543)/2") == true
>> stacktrace:
>> (elixir) lib/keyword.ex:195: Keyword.get/3
>> (elixir) lib/string.ex:1372: String.replace/4
>> (bracket_push) lib/bracket_push.ex:15: BracketPush.check_brackets/
>> 1
>> test/bracket_push_test.exs:53: (test)
>>
>> test/bracket_push_test.exs:52
>> ** (FunctionClauseError) no function clause matching in Keyword.get/
>> 3
>> The following arguments were given to Keyword.get/3:
>>
>>
>> # 1
>>
>> ""
>>
>>
>> # 2
>> :insert_replaced
>>
>>
>> # 3
>> nil
>>
>>
>> Attempted function clauses (showing 1 out of 1):
>>
>>
>> def get(keywords, key, default) when is_list(keywords) and
>> is_atom(key)
>>
>>
>> code: assert BracketPush.check_brackets("(((185 + 223.85) * 15) -
>> 543)/2") == true
>> stacktrace:
>> (elixir) lib/keyword.ex:195: Keyword.get/3
>> (elixir) lib/string.ex:1372: String.replace/4
>> (bracket_push) lib/bracket_push.ex:15: BracketPush.check_brackets/
>> 1
>>
>> As a new language user, it's really hard to understand what I did wrong
>> when the error is thrown from inside the inner implementation of
>> String.replace/4. In order to debug this, I'd either have to look at the
>> inner implementation of String.replace/4 or attempt to fiddle with the
>> arguments. My preference would be for standard library functions to guard
>> their own interfaces, and throw specific and actionable messages back to
>> the developer.
>>
>> Thanks for taking the time to read!
>>
>>
> --
> Kind regards,
> Dmitry Belyaev
>
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