diff options
Diffstat (limited to 'docs/commentary/problems.html')
| -rw-r--r-- | docs/commentary/problems.html | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/docs/commentary/problems.html b/docs/commentary/problems.html index f74aabde..fbdd6eb5 100644 --- a/docs/commentary/problems.html +++ b/docs/commentary/problems.html @@ -81,7 +81,7 @@ <h3 id="prefixessuffixes-add-depth-and-windows-doesnt">Prefixes/Suffixes add depth and Windows doesn't</h3> <p>It's an awkward inconsistency. Prefixes and Suffixes have to have a nested result, but Windows doesn't have to be flat; it's just that making it nested ignores the fact that it does have an array structure.</p> <h3 id="deshape-and-reshape-cant-ignore-trailing-axes">Deshape and Reshape can't ignore trailing axes</h3> -<p>If you want to repeat 3 major cells until there are 7 of them, or combine the first 4 axes of a rank-6 array, what's your best option? Nothing's too good: you could compute a full shape for Reshape, enclose cells and merge afterwards, use Select to reshape one axis to multiple, or use <code><span class='Function'>∾</span><span class='Modifier'>˝</span></code> to merge two axes (with possible empty-array issues). This is particularly dangerous with computed-length reshapes like <code><span class='Number'>2</span><span class='Ligature'>‿</span><span class='Modifier2'>∘</span><span class='Function'>⥊</span><span class='Value'>…</span></code>, since the idea of splitting off a length-2 axis from an array's first axis is generally useful, but this version has an implicit Deshape first. J's Reshape analogue (<code><span class='Value'>$</span></code>) only ever applies to the first axis. This also seems to be giving up a lot.</p> +<p>If you want to repeat 3 major cells until there are 7 of them, or combine the first 4 axes of a rank-6 array, what's your best option? Nothing's too good: you could compute a full shape for Reshape, enclose cells and merge afterwards (for example <code><span class='Number'>7</span><span class='Modifier2'>⊸</span><span class='Function'>⥊</span><span class='Modifier2'>⌾</span><span class='Paren'>(</span><span class='Function'><</span><span class='Modifier'>˘</span><span class='Paren'>)</span></code>), use Select to reshape one axis to multiple, or use <code><span class='Function'>∾</span><span class='Modifier'>˝</span></code> to merge two axes (with possible empty-array issues). This is particularly dangerous with computed-length reshapes like <code><span class='Number'>2</span><span class='Ligature'>‿</span><span class='Modifier2'>∘</span><span class='Function'>⥊</span><span class='Value'>…</span></code>, since the idea of splitting off a length-2 axis from an array's first axis is generally useful, but this version has an implicit Deshape first. J's Reshape analogue (<code><span class='Value'>$</span></code>) only ever applies to the first axis. This also seems to be giving up a lot.</p> <h3 id="at-which-scope-does-a-block-function-belong">At which scope does a block function belong?</h3> <p>As a general principle, a programmer should make choices in one part of a program that constrain other parts of the program most tightly. This is a weak principle, but often it doesn't conflict with any other preferences and can be followed for free. For example it's usually best to define a variable in the smallest possible scope, so the reader knows it isn't used outside that scope. The same principle applies to blocks, but there is another conflicting principle: placing the block in a broader scope guarantees it won't access the variables in narrower ones. There's no position that will tell the reader, for example, that a function only uses variables local to itself and that it's only used within one particular scope.</p> <p>This is an issue with any lexically-scoped language; it's unlikely BQN can solve it. On the other hand, I'm surprised I've never seen any discussion of such a universal issue.</p> |