I am VERY much an elixir newbie. I have taken one elixir course and one phoenix course on Udemy. During that course, I saw the instructor do a pattern match against a string. This is exactly the first step i needs to take for my first phoenix project. in my project, I am receiving a ton of strings …

Unless you know exactly how many characters your artist has you’ll need to resort to using regex or some other tool for parsing the string. Pattern matches cannot do what you seem to be looking for.

[image] sergio_101: ** (ArgumentError) the left argument of <> operator inside a match should be always a literal binary as its size can’t be verified, got: artist That error is complaining about this part of your code specifically: artist <> "(" The way matching on binaries works is that: …

[image] LostKobrakai: you’ll need to resort to using regex or some other tool for parsing the string Almost true :slight_smile: defmodule Matcher do for artist_len <- 1..100, num_len <- 1..10 do def li(<< "<li>", artist :: binary-size(unquote(artist_len)), …

okay, this is assuming that the data matches the length requirement in line 2? in the example i saw, it was something simple like: iex(6)> s = "categories:1" "categories:1" iex(7)> "categories:"<>index=s "categories:1" iex(8)> index "1" I’ll give this a shot. Thanks!

[image] sergio_101: this is assuming that the data matches the length requirement in line 2? Nope. The code above generates 1001 functions handling all possible combinations of lengths for artist and num in the intervals 1..100 and 1..10 respectively. Plus one sink-all clause in the lengths …

[image] mudasobwa: The code above generates 1001 functions Close, but wrong :wink: it generates a single function with 1001 heads.

[image] NobbZ: a single function with 1001 heads Indeed. We call it Matching Dragon.

okay.. so, my next question. is there something more “functional” about doing it this way, rather than a straight pattern match? i have spent the past 30 years in the OOP world. I used Lisp maybe 30 years ago, but didn’t know enough to really make the distinction back then. I know I initially asked…

[image] sergio_101: doing it this way, rather than a straight pattern match? You probably meant “rather than a straight regex.” Well, it depends . In most cases Regex is just fine. Also, if you are after parsing the (contrived example) ISO8601 representation of a date, you might extract year,…

If these are guaranteed to be small HTML pieces I’d parse them with Floki or Meeseks and then apply a simpler regex on the text to get the two pieces of data you require. Regex for HTML or XML is a hard “NO!” even if you do a two-days educational throwaway project.