From d061b6cc5060eb12a22fe89660fc0ae2b3c397f7 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Fri, 5 Jun 2020 20:17:52 -0400
Subject: More and better Dyalog conversion tables

---
 FromDyalog.md | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/FromDyalog.md b/FromDyalog.md
index 5ea3a6c4..3ec2800f 100644
--- a/FromDyalog.md
+++ b/FromDyalog.md
@@ -1,3 +1,7 @@
+A few tables to help users of Dyalog APL (or similar) get started quickly on BQN.
+
+## For reading
+
 Here are some closest equivalents in Dyalog APL for the BQN functions that don't use the same glyphs as APL. Correspondence can be approximate, and `⌽` is just used as a decorator to mean "reverse some things".
 
 | BQN   | `⋆` | `√`    | `∧`   | `∨`   | `¬`   | `≠` | `<` | `>` | `≢` | `⥊` | `∾`   | `≍`    |
@@ -9,3 +13,75 @@ Here are some closest equivalents in Dyalog APL for the BQN functions that don't
 |-------|------|---------|------|-----|-----|-----|-------|------|-----|-----|-----|-----|-----|-----|
 | Monad | `,⍀` | `⌽,⌽⍀⌽` | `⍳`  | `⍸` |     | `⍋` | `⍒`   | `⊣⌿` | `⊃` |     | `…` | `≠` |     | `⌸` |
 | Dyad  | `↑`  | `↓`     | `,⌿` | `⌿` | `⊆` | `⍸` | `⌽⍸⌽` | `⌷`  |     | `⍳` | `…` | `∊` | `⍷` |     |
+
+Modifiers and combinators are a little harder. Many have equivalents in some cases, but Dyalog sometimes chooses different functionality based on whether the operand is an array. In BQN an array is always treated as a constant function.
+
+| BQN    | `¨` | `⌜`  | `´` | `⎉` | `⍟` | `˜` | `∘` | `○` | `⟜` |
+|--------|-----|------|-----|-----|-----|-----|-----|-----|-----|
+| Dyalog | `¨` | `∘.` | `⌿` | `⍤` | `⍣` | `⍨` | `⍤` | `⍥` | `∘` |
+
+In BQN `⎉` is Rank and `∘` is Atop. Dyalog's Atop (`⍤`) and Over (`⍥`) were added in version 18.0.
+
+## For writing
+
+The tables below give approximate implementations of Dyalog primitives for the ones that aren't the same. First- and last-axis pairs are also mostly omitted. BQN just has the first-axis form, and you can get the last-axis form with `⎉1`.
+
+<table>
+<tr><th colspan=3>Functions</th></tr>
+<tr><th> Glyph            </th><th> Monadic                      </th><th> Dyadic </th>               </tr>
+<tr><td> <code>*</code>   </td><td colspan=2><code>⋆</code></td>                                      </tr>
+<tr><td> <code>⍟</code>   </td><td colspan=2><code>⋆⁼</code></td>                                     </tr>
+<tr><td> <code>!</code>   </td><td colspan=2>Implement it yourself</td>                               </tr>
+<tr><td> <code>○</code>   </td><td colspan=2>Some complex exponential stuff, maybe</td>               </tr>
+<tr><td> <code>~</code>   </td><td> <code>¬</code>               </td><td> <code>¬∘∊/⊣</code></td>    </tr>
+<tr><td> <code>?</code>   </td><td colspan=2>Library?</td>                                            </tr>
+<tr><td> <code>⍲</code>   </td><td>                   </td>           <td> <code>¬∘∧</code></td>      </tr>
+<tr><td> <code>⍱</code>   </td><td>                   </td>           <td> <code>¬∘∨</code></td>      </tr>
+<tr><td> <code>⍴</code>   </td><td> <code>≢</code>               </td><td> <code>⥊</code></td>        </tr>
+<tr><td> <code>,</code>   </td><td> <code>⥊</code>               </td><td> <code>∾⎉1</code></td>      </tr>
+<tr><td> <code>⍪</code>   </td><td> <code>∾˘</code>              </td><td> <code>∾</code></td>        </tr>
+<tr><td> <code>↑</code>   </td><td> <code>></code>               </td><td> <code>↑</code></td>        </tr>
+<tr><td> <code>↓</code>   </td><td> <code><˘<code>              </td> <td> <code>↑</code></td>        </tr>
+<tr><td> <code>⊂</code>   </td><td> <code><<code>               </td> <td> <code>\</code></td>        </tr>
+<tr><td> <code>⊆</code>   </td><td> <code><⍟(0<≡)<code>         </td> <td> <code>\</code></td>        </tr>
+<tr><td> <code>∊</code>   </td><td> <code>{0=≡𝕩:⥊𝕩⋄∾⥊∇¨𝕩}</code> </td><td> <code>∊</code></td>        </tr>
+<tr><td> <code>⊃</code>   </td><td colspan=2><code>⊑</code></td>                                      </tr>
+<tr><td> <code>⍀</code>   </td><td>                   </td>           <td> <code>/⁼</code></td>       </tr>
+<tr><td> <code>∩</code>   </td><td>                   </td>           <td> <code>∊/⊣</code></td>      </tr>
+<tr><td> <code>∪</code>   </td><td> <code>∊⊸/</code>             </td><td> <code>⊣∾∊˜¬⊸/⊢</code></td> </tr>
+<tr><td> <code>⍳</code>   </td><td> <code>↕</code>               </td><td> <code>⊐</code></td>        </tr>
+<tr><td> <code>⍸</code>   </td><td> <code>/</code>               </td><td> <code>⍋</code></td>        </tr>
+<tr><td> <code>⍋</code>   </td><td> <code>⍋</code>               </td><td> Give up</td>               </tr>
+<tr><td> <code>⍒</code>   </td><td> <code>⍒</code>               </td><td> Give up</td>               </tr>
+<tr><td> <code>≢</code>   </td><td> <code>≠</code>               </td><td> <code>≢</code></td>        </tr>
+<tr><td> <code>⍎</code>   </td><td colspan=2 rowspan=2>To be decided</td>                             </tr>
+<tr><td> <code>⍕</code>   </td>                                                                       </tr>
+<tr><td> <code>⊥</code>   </td><td>                   </td>           <td rowspan=2>To be decided</td></tr>
+<tr><td> <code>⊤</code>   </td><td>                   </td>                                           </tr>
+<tr><td> <code>⌹</code>   </td><td colspan=2><code>+´∘×⎉1‿∞⁼</code> I guess</td>                      </tr>
+<tr><td> <code>⌷</code>   </td><td> N/A               </td>           <td> <code>⊏</code></td>        </tr>
+</table>
+
+<table>
+<tr><th colspan=3>Operators</th></tr>
+<tr><th> Syntax           </th><th> Monadic          </th><th> Dyadic                </th></tr>
+<tr><td> <code>⌿</code>   </td><td> <code>´</code>   </td><td> <code>↕</code>        </td></tr>
+<tr><td> <code>⍀</code>   </td><td colspan=2> <code>↑</code> or <code>`</code>       </td></tr>
+<tr><td> <code>¨</code>   </td><td colspan=2> <code>¨</code>                         </td></tr>
+<tr><td> <code>⍨</code>   </td><td colspan=2> <code>˜</code>                         </td></tr>
+<tr><td> <code>⍣</code>   </td><td colspan=2> <code>⍟</code>                         </td></tr>
+<tr><td> <code>f.g</code> </td><td>                  </td><td> <code>f´∘g⍟1‿∞</code> </td></tr>
+<tr><td> <code>∘.f</code> </td><td>                  </td><td> <code>f⌜</code>       </td></tr>
+<tr><td> <code>A∘g</code> </td><td> <code>A⊸g</code> </td><td>                       </td></tr>
+<tr><td> <code>f∘B</code> </td><td> <code>f⟜B</code> </td><td>                       </td></tr>
+<tr><td> <code>f∘g</code> </td><td colspan=2> <code>f⟜g</code>                       </td></tr>
+<tr><td> <code>f⍤B</code> </td><td colspan=2> <code>f⎉B</code>                       </td></tr>
+<tr><td> <code>f⍤g</code> </td><td colspan=2> <code>f∘g</code>                       </td></tr>
+<tr><td> <code>f⍥g</code> </td><td colspan=2> <code>f○g</code>                       </td></tr>
+<tr><td> <code>f@v</code> </td><td colspan=2> <code>f⌾(v⊸⊏)</code>                   </td></tr>
+<tr><td> <code>f⍠B</code> </td><td colspan=2> Uh                                     </td></tr>
+<tr><td> <code>f⌸</code>  </td><td colspan=2> <code>⊔</code>                         </td></tr>
+<tr><td> <code>f⌺B</code> </td><td colspan=2> <code>↕</code>                         </td></tr>
+<tr><td> <code>A⌶</code>  </td><td colspan=2> <code>•</code>                         </td></tr>
+<tr><td> <code>f&</code>  </td><td colspan=2> Nothing yet                            </td></tr>
+</table>
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