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!
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