From 224d6ed83efb86fa16ac802af65c63d1b97543e2 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Sat, 29 Jan 2022 17:48:16 -0500
Subject: More detail in a few help pages

---
 help/depth.md             | 4 +++-
 help/leftargument.md      | 8 ++++++++
 help/length_notequals.md  | 2 ++
 help/merge_greaterthan.md | 6 ++----
 help/nothing.md           | 8 ++++++--
 help/rank.md              | 2 +-
 help/rank_equals.md       | 2 ++
 7 files changed, 24 insertions(+), 8 deletions(-)

(limited to 'help')

diff --git a/help/depth.md b/help/depth.md
index 8c0d4367..bbe4d297 100644
--- a/help/depth.md
+++ b/help/depth.md
@@ -5,9 +5,11 @@
 ## `𝔽⚇𝕘 𝕩`, `𝕨 𝔽⚇𝕘 𝕩`: Depth
 [→full documentation](../doc/depth.md#the-depth-modifier)
 
-Apply `𝔽` to the cells of the arguments at depth given in `𝕘`.
+Apply `𝔽` to the cells of the arguments at depth given in `𝕘`. Negative numbers count down from the top level and non-negative ones from the bottom up.
 
 
         1⊸↓⚇1 ⟨⟨1,2,3⟩, ⟨4,5,6⟩⟩
 
         1 ↓⚇1 ⟨⟨1,2,3⟩, ⟨4,5,6⟩⟩
+
+        (+´↕)⚇0 ⟨2,4‿7,3⟩  # Implements pervasion
diff --git a/help/leftargument.md b/help/leftargument.md
index f8031f26..bda7fedc 100644
--- a/help/leftargument.md
+++ b/help/leftargument.md
@@ -8,3 +8,11 @@
 A variable assigned to the left argument of a block. `𝕎` can be used to access the left argument as a function.
 
         5 {𝕨} 1
+
+        -‿÷ {𝕎𝕩}¨ 4
+
+In a call with no left argument, `𝕨` functions as [Nothing](nothing.md) and `𝕎` can't be used.
+
+        {(-𝕨)⋈𝕩} 6
+
+        2 {(-𝕨)⋈𝕩} 6
diff --git a/help/length_notequals.md b/help/length_notequals.md
index 5d17237c..e13a14fe 100644
--- a/help/length_notequals.md
+++ b/help/length_notequals.md
@@ -23,6 +23,8 @@ Length of the first dimension of `𝕩`.
 ## `𝕨 ≠ 𝕩`: Not Equal To
 [→full documentation](../doc/arithmetic.md#comparisons)
 
+Do argument atoms not match?
+
 [Pervasive.](../doc/arithmetic.md#pervasion)
 
         1 ≠ 3
diff --git a/help/merge_greaterthan.md b/help/merge_greaterthan.md
index ee315fca..e78c063a 100644
--- a/help/merge_greaterthan.md
+++ b/help/merge_greaterthan.md
@@ -5,11 +5,9 @@
 ## `> 𝕩`: Merge
 [→full documentation](../doc/couple.md)
 
-Add the rank of an element of `𝕩` to the rank of `𝕩`.
+Combine an array of arrays into one array. All elements of `𝕩` must have the same rank, and the result rank is that plus the rank of `𝕩`.
 
-All elements must have the same rank.
-
-Returns atomic values as is.
+Returns and boxed atoms unchanged.
 
 
         a ← ⟨⟨1, 2⟩, ⟨3, 4⟩⟩
diff --git a/help/nothing.md b/help/nothing.md
index 0a5ad783..23aee6ba 100644
--- a/help/nothing.md
+++ b/help/nothing.md
@@ -5,6 +5,10 @@
 ## `·`: Nothing
 [→full documentation](../doc/expression.md#nothing)
 
+Indicates no value. If a left argument is Nothing, the function is called with no left argument, and if the right is Nothing, it's not called and "returns" Nothing.
+
+        · ⌽ "abc"  # Reverse instead of Rotate
+
 ### In Trains
 
 Nothing can serve as a left argument in a train to string together multiple monadic functions.
@@ -13,9 +17,9 @@ Nothing can serve as a left argument in a train to string together multiple mona
 
         (-·+-) 5
 
-### In Block Headers
+### Destructuring
 
-For Block header pattern matching syntax, Nothing can be used to indicate an unused value.
+For pattern matching in assignment or a block header, Nothing indicates an unused value.
 
         F ← {𝕊 a‿·‿b: a∾b}
 
diff --git a/help/rank.md b/help/rank.md
index 8f9e83ac..a3dddaf5 100644
--- a/help/rank.md
+++ b/help/rank.md
@@ -4,7 +4,7 @@
 
 ## `𝔽⎉𝕘 𝕩`, `𝕨 𝔽⎉𝕘 𝕩`: Rank
 
-Apply `𝔽` to cells at ranks given in `𝕘`.
+Apply `𝔽` to cells at ranks given in `𝕘`. Non-negative numbers indicate the rank of the cell and negative ones indicate the difference from full rank.
 
 The ranks applied are given by the following:
 
diff --git a/help/rank_equals.md b/help/rank_equals.md
index 0f41f6fa..ed590408 100644
--- a/help/rank_equals.md
+++ b/help/rank_equals.md
@@ -21,6 +21,8 @@ Returns the number of dimensions in `𝕩`.
 ## `𝕨 = 𝕩`: Equal To
 [→full documentation](../doc/arithmetic.md#comparisons)
 
+Do argument atoms match?
+
 [Pervasive.](../doc/arithmetic.md#pervasion)
 
         1 = 3
-- 
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