feat(tooling): add dialyxir and fix all dialyzer warnings

- Add dialyxir ~> 1.4 as a dev dependency
- Add @type t to CodeQA.Pipeline.FileContext so the type is resolvable
- Remove nan?/1 helper (BEAM has no NaN floats, made not nan?() always true)
- Remove redundant is_float/1 check in keep_correlation? (pearson always returns float)
- Simplify maybe_add/3 to a single-clause if expression

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: aspala

lib/codeqa/cli.ex

@@ -501,7 +501,7 @@ defmodule CodeQA.CLI do
   end
 
   defp keep_correlation?(corr, opts) do
-    valid = is_float(corr) and not nan?(corr) and corr != 0.0
+    valid = corr != 0.0
     valid = if opts[:hide_exact], do: valid and abs(corr) != 1.0, else: valid
     valid = if valid and opts[:min], do: corr >= opts[:min], else: valid
     if valid and opts[:max], do: corr <= opts[:max], else: valid
@@ -895,13 +895,9 @@ defmodule CodeQA.CLI do
     end)
   end
 
-  defp maybe_add(opts, nil, _item), do: opts
-  defp maybe_add(opts, false, _item), do: opts
-  defp maybe_add(opts, _truthy, item), do: [item | opts]
-
-  # IEEE 754: NaN != NaN — Credo false positive (comparison IS meaningful for NaN)
-  # credo:disable-for-next-line Credo.Check.Warning.OperationOnSameValues
-  defp nan?(x), do: x != x
+  defp maybe_add(opts, val, item) do
+    if val, do: [item | opts], else: opts
+  end
 
   defp parse_ignore_paths(nil), do: []
 

lib/codeqa/pipeline.ex

@@ -15,6 +15,18 @@ defmodule CodeQA.Pipeline do
       :line_count
     ]
     defstruct @enforce_keys
+
+    @type t :: %__MODULE__{
+      content: String.t(),
+      tokens: tuple(),
+      token_counts: map(),
+      words: tuple(),
+      identifiers: tuple(),
+      lines: tuple(),
+      encoded: String.t(),
+      byte_count: non_neg_integer(),
+      line_count: non_neg_integer()
+    }
   end
 
   @word_re ~r/\b[a-zA-Z_]\w*\b/u

mix.exs

@@ -29,7 +29,8 @@ defmodule CodeQA.MixProject do
       {:flow, "~> 1.2"},
       {:yaml_elixir, "~> 2.11"},
       {:ex_doc, "~> 0.34", only: :dev, runtime: false},
-      {:credo, "~> 1.7", only: :dev, runtime: false}
+      {:credo, "~> 1.7", only: :dev, runtime: false},
+      {:dialyxir, "~> 1.4", only: :dev, runtime: false}
     ]
   end
 end

mix.lock

@@ -2,7 +2,9 @@
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
   "complex": {:hex, :complex, "0.6.0", "b0130086a7a8c33574d293b2e0e250f4685580418eac52a5658a4bd148f3ccf1", [:mix], [], "hexpm", "0a5fa95580dcaf30fcd60fe1aaf24327c0fe401e98c24d892e172e79498269f9"},
   "credo": {:hex, :credo, "1.7.17", "f92b6aa5b26301eaa5a35e4d48ebf5aa1e7094ac00ae38f87086c562caf8a22f", [:mix], [{:bunt, "~> 0.2.1 or ~> 1.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "1eb5645c835f0b6c9b5410f94b5a185057bcf6d62a9c2b476da971cde8749645"},
+  "dialyxir": {:hex, :dialyxir, "1.4.7", "dda948fcee52962e4b6c5b4b16b2d8fa7d50d8645bbae8b8685c3f9ecb7f5f4d", [:mix], [{:erlex, ">= 0.2.8", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "b34527202e6eb8cee198efec110996c25c5898f43a4094df157f8d28f27d9efe"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.44", "f20830dd6b5c77afe2b063777ddbbff09f9759396500cdbe7523efd58d7a339c", [:mix], [], "hexpm", "4778ac752b4701a5599215f7030989c989ffdc4f6df457c5f36938cc2d2a2750"},
+  "erlex": {:hex, :erlex, "0.2.8", "cd8116f20f3c0afe376d1e8d1f0ae2452337729f68be016ea544a72f767d9c12", [:mix], [], "hexpm", "9d66ff9fedf69e49dc3fd12831e12a8a37b76f8651dd21cd45fcf5561a8a7590"},
   "ex_doc": {:hex, :ex_doc, "0.40.1", "67542e4b6dde74811cfd580e2c0149b78010fd13001fda7cfeb2b2c2ffb1344d", [:mix], [{:earmark_parser, "~> 1.4.44", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "bcef0e2d360d93ac19f01a85d58f91752d930c0a30e2681145feea6bd3516e00"},
   "file_system": {:hex, :file_system, "1.1.1", "31864f4685b0148f25bd3fbef2b1228457c0c89024ad67f7a81a3ffbc0bbad3a", [:mix], [], "hexpm", "7a15ff97dfe526aeefb090a7a9d3d03aa907e100e262a0f8f7746b78f8f87a5d"},
   "flow": {:hex, :flow, "1.2.4", "1dd58918287eb286656008777cb32714b5123d3855956f29aa141ebae456922d", [:mix], [{:gen_stage, "~> 1.0", [hex: :gen_stage, repo: "hexpm", optional: false]}], "hexpm", "874adde96368e71870f3510b91e35bc31652291858c86c0e75359cbdd35eb211"},