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]> 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! > >-- >You received this message because you are subscribed to the Google >Groups "elixir-lang-core" group. >To unsubscribe from this group and stop receiving emails from it, send >an email to [email protected]. >To view this discussion on the web visit >https://groups.google.com/d/msgid/elixir-lang-core/ec0892c5-04b8-4fe7-88b5-e12312483fa6%40googlegroups.com. -- Kind regards, Dmitry Belyaev -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/03040498-4D0B-4DAE-B8FC-11317F6210CE%40gmail.com.
