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Patrick pushed to branch wip/T25647 at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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Commits:
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<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4e87344bac87bf9350453c222ab670a32ed24815">4e87344b</a></strong>
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<span> by Patrick </span> <i> at 2025-03-05T10:45:34+08:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Refine documentation on wildcard handling in type families and clarify design choices for FamArgFlavour
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1 changed file:
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compiler/GHC/Core/TyCon.hs
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Changes:
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<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4e87344bac87bf9350453c222ab670a32ed24815#4aad0050db1a8a20db8bbca149111de99cb299c9"><strong style="font-weight: 600;">compiler/GHC/Core/TyCon.hs</strong></a>
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<td class="diff-line-num unfold js-unfold old_line" data-linenumber="2985" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="diff-line-num unfold js-unfold new_line" data-linenumber="2985" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="line_content match" style="color: rgba(5,5,6,.24); padding: inherit;" bgcolor="#fbfafd">@@ -2985,27 +2985,31 @@ Wildcards in type families are used to represent type/kind information that</td>
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<td class="old_line diff-line-num" data-linenumber="2985" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2985
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<td class="new_line diff-line-num" data-linenumber="2985" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2985
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2985" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">are not specified by the user. It is controversial how to interpret wildcards</span></span>
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<td class="old_line diff-line-num" data-linenumber="2986" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2986
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<td class="new_line diff-line-num" data-linenumber="2986" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2986
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2986" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">in type families. Hence We classify kinds of wildcards in type families into</span></span>
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<td class="old_line diff-line-num" data-linenumber="2987" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2987
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<td class="new_line diff-line-num" data-linenumber="2987" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2987
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2987" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">three categories represented by the FamArgFlavour data type: ClassArg, FreeArg,</span></span>
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<td class="old_line diff-line-num old" data-linenumber="2988" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
2988
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<td class="new_line diff-line-num old" data-linenumber="2988" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC2988" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">and SigArg, see Note [FamArgFlavour] for more detail. <span class="idiff left right deletion" style="background-color: #fac5cd;"> </span>This flexibility allows</span></span>
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<td class="old_line diff-line-num new" data-linenumber="2989" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="2988" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
2988
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC2988" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">and SigArg, see Note [FamArgFlavour] for more detail. This flexibility allows</span></span>
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2989
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<td class="new_line diff-line-num" data-linenumber="2989" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2989
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2989" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">us to flip the interpretation of wildcards in type families.</span></span>
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2990
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2990
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2990" class="line" lang="haskell"></span>
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2991
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<td class="new_line diff-line-num" data-linenumber="2991" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2991
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2991" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Some common agreements:</span></span>
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2992
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2992
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2992" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num old" data-linenumber="2993" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
2993
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<td class="new_line diff-line-num old" data-linenumber="2993" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC2993" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">* <span class="idiff left right deletion" style="background-color: #fac5cd;">W</span>ildcards should be not defaulted.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="2993" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
2993
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC2993" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">* <span class="idiff left right addition" style="background-color: #c7f0d2;">FreeArg w</span>ildcards should be not defaulted.</span></span>
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2994
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2994
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2994" class="line" lang="haskell"></span>
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2995
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<td class="new_line diff-line-num old" data-linenumber="2995" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC2995" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">* For `ClassArg`, it should be able to represent atleast arbitrary type variables, it is</span></span>
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<td class="new_line diff-line-num new" data-linenumber="2995" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
2995
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC2995" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">* For `ClassArg`, it should be able to represent at<span class="idiff left right addition" style="background-color: #c7f0d2;"> </span>least arbitrary type variables, it is</span></span>
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2996
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2996
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2996" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;"> used in our codebase.</span></span>
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2997
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2997
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2997" class="line" lang="haskell"></span>
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2998
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<td class="new_line diff-line-num" data-linenumber="2998" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
2998
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2998" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;"> instance (HasDefaultDiagnosticOpts opts, Outputable hint) => Diagnostic (UnknownDiagnostic opts hint) where</span></span>
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2999
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2999
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC2999" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;"> type DiagnosticOpts (UnknownDiagnostic opts _) = opts</span></span>
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3000
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3000
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3000" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;"> type DiagnosticHint (UnknownDiagnostic _ hint) = hint</span></span>
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3001
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3001
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3001" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num old" data-linenumber="3002" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
3002
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<td class="new_line diff-line-num old" data-linenumber="3002" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3002" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">* For `SigArg`, it should be able to represent atleast arbitrary type variables.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3002" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3002
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3002" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">By picking different type var for different flavours of wildcards in `tcAnonWildCardOcc`, we can</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3003" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3003
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3003" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">explore different design spaces. For example, we can have the following design spaces:</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3004" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3004
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3004" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">1. Wildcards can represet arbitrary types, including type variables, picks TauTv.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3005" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3005
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3005" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">2. Wildcards can only represent type variables, picks TyVarTv.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3006" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3006
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3006" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">3. Wildcards stand alone, pick skolemTv variables.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3007" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3007
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3007" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">... and so on.</span></span>
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3003
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<td class="new_line diff-line-num" data-linenumber="3008" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3008
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3008" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num old" data-linenumber="3004" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
3004
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<td class="new_line diff-line-num old" data-linenumber="3009" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3004" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">We have two design choices:</span></span>
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3005
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<td class="new_line diff-line-num old" data-linenumber="3009" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3005" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">1. Wildcards can represet arbitrary types, including type variables.</span></span>
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3006
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<td class="new_line diff-line-num old" data-linenumber="3009" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3006" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">2. Wildcards can only represent type variables.</span></span>
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3007
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3007" class="line" lang="haskell"></span>
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3008
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<td class="new_line diff-line-num old" data-linenumber="3009" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3008" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">... todo add more</span></span>
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3009
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3009" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Maintaining backward compatibility, the current picks:</span></span>
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3010
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3010" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">- TyVarTv for FreeArg</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3011" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3011
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3011" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">- TauTv for ClassArg</span></span>
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3012
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3012" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">- TauTv for SigArg</span></span>
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3009
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3013
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3013" class="line" lang="haskell"></span>
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3010
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<td class="new_line diff-line-num" data-linenumber="3014" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3014
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3014" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">For more discussion, see #13908.</span></span>
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3011
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3015
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3015" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">-}</span></span>
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<td class="diff-line-num unfold js-unfold old_line" data-linenumber="3043" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="diff-line-num unfold js-unfold new_line" data-linenumber="3047" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">...</td>
<td class="line_content match" style="color: rgba(5,5,6,.24); padding: inherit;" bgcolor="#fbfafd">@@ -3043,22 +3047,19 @@ For instance, for an instance declaration like</td>
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3043
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<td class="new_line diff-line-num" data-linenumber="3047" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3047
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3047" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">the first two underscores (free arguments) would yield TyVarTv’s while the last two underscores (a class</span></span>
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3044
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<td class="new_line diff-line-num" data-linenumber="3048" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3048
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3048" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">argument and a signature argument) would produce TauTv's.</span></span>
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3045
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3049
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3049" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num old" data-linenumber="3046" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
3046
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<td class="new_line diff-line-num old" data-linenumber="3050" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3046" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">This design provides flexibility in handling wildcards in type families.</span></span>
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3047
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3047" class="line" lang="haskell"></span>
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3048
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<td class="new_line diff-line-num" data-linenumber="3050" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3050
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3050" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">[More on SigArg]</span></span>
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3049
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3051
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3051" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Example from T14366</span></span>
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3050
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3052
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3052" class="line" lang="haskell"></span>
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<td class="new_line diff-line-num" data-linenumber="3053" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3053
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3053" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">type family F (a :: Type) :: Type where</span></span>
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3054
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3054" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;"> F (a :: _) = a</span></span>
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3054" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Imagine without SigArg, since F is non-associated, every argument is <span class="idiff left deletion" style="background-color: #fac5cd;">f</span>ree<span class="idiff right deletion" style="background-color: #fac5cd;">Var</span>,</span></span>
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3055
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<td class="new_line diff-line-num old" data-linenumber="3056" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3055" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">now let's consider _ here as a <span class="idiff left deletion" style="background-color: #fac5cd;">f</span>ree<span class="idiff right deletion" style="background-color: #fac5cd;">Var</span> then TyVarTv, then it would not match Type.</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3056" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3056
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3056" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Imagine without SigArg, since F is non-associated, every argument is <span class="idiff left addition" style="background-color: #c7f0d2;">F</span>ree<span class="idiff right addition" style="background-color: #c7f0d2;">Arg</span>,</span></span>
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<td class="new_line diff-line-num new" data-linenumber="3057" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3057
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3057" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">now let's consider _ here as a <span class="idiff left addition" style="background-color: #c7f0d2;">F</span>ree<span class="idiff right addition" style="background-color: #c7f0d2;">Arg</span> then TyVarTv, then it would not match Type.</span></span>
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3056
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<td class="new_line diff-line-num" data-linenumber="3058" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3058
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3058" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Say if we assign ClassArg to _ here, if we want to flip class arguments in associated</span></span>
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3057
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<td class="new_line diff-line-num" data-linenumber="3059" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3059
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3059" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">type family to only match Type variables. Then this example would not work.</span></span>
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3058
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<td class="new_line diff-line-num" data-linenumber="3060" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3060
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3060" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num old" data-linenumber="3059" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
3059
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<td class="new_line diff-line-num old" data-linenumber="3061" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3059" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Hence we maintain diffirent flavours between class arguments and signature arguments</span></span>
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<td class="old_line diff-line-num old" data-linenumber="3060" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
3060
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<td class="new_line diff-line-num old" data-linenumber="3061" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3060" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">because we want to be able to flip only the true class arguments without affecting</span></span>
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3061
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<td class="new_line diff-line-num old" data-linenumber="3061" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC3061" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">the signature arguments.</span></span>
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<td class="old_line diff-line-num new" data-linenumber="3062" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="3061" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3061
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3061" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">Hence we maintain three different flavours of wildcards in type families. This provides</span></span>
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<td class="old_line diff-line-num new" data-linenumber="3062" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="new_line diff-line-num new" data-linenumber="3062" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
3062
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC3062" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">a flexibility to interpret wildcards in type families.</span></span>
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3062
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<td class="new_line diff-line-num" data-linenumber="3063" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3063
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3063" class="line" lang="haskell"></span>
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<td class="old_line diff-line-num" data-linenumber="3063" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3063
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<td class="new_line diff-line-num" data-linenumber="3064" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3064
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3064" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">For more discussion, see #13908.</span></span>
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3064
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<td class="new_line diff-line-num" data-linenumber="3065" style="width: 35px; color: rgba(5,5,6,.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
3065
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #3a383f; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; font-variant-ligatures: none; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC3065" class="line" lang="haskell"><span class="cm" style="color: #999988; font-style: italic;">-}</span></span>
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