Simple examples: Difference between revisions
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Miraheze>Adám Brudzewsky |
Miraheze>Adám Brudzewsky No edit summary |
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This page will contain examples that serve well to show APL's strength. They require minimal background and have no special dependencies. | This page will contain examples that serve well to show APL's strength. They require minimal background and have no special dependencies. | ||
=== Indices of multiple elements === | |||
APL represents text as character lists (vectors), making many text operations trivial: | |||
<code class="apl">∊</code> gives us a mask for elements (characters) in the left argument that are members of the right argument: | |||
<pre class=apl> | |||
'mississippi'∊'sp' | |||
0 0 1 1 0 1 1 0 1 1 0 | |||
</pre> | |||
<code class="apl">⍸</code> gives us the indices where true (1): | |||
<pre class=apl> | |||
⍸'mississippi'∊'sp' | |||
3 4 6 7 9 10 | |||
</pre> | |||
We can combine this into an anonymous infix (dyadic) function: | |||
<pre class=apl> | |||
'mississippi' (⍸∊) 'sp' | |||
3 4 6 7 9 10 | |||
</pre> | |||
=== Parenthesis nesting level === | === Parenthesis nesting level === | ||
<pre class=apl> | <pre class=apl> | ||
| Line 6: | Line 23: | ||
</pre> | </pre> | ||
{{APL programming language}} | {{APL programming language}} | ||
Revision as of 15:24, 10 October 2019
This page will contain examples that serve well to show APL's strength. They require minimal background and have no special dependencies.
Indices of multiple elements
APL represents text as character lists (vectors), making many text operations trivial:
∊ gives us a mask for elements (characters) in the left argument that are members of the right argument:
'mississippi'∊'sp' 0 0 1 1 0 1 1 0 1 1 0
⍸ gives us the indices where true (1):
⍸'mississippi'∊'sp' 3 4 6 7 9 10
We can combine this into an anonymous infix (dyadic) function:
'mississippi' (⍸∊) 'sp' 3 4 6 7 9 10
Parenthesis nesting level
+\-⌿'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' 0 0 0 0 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 2 2 2 2 2 2 2 3 3 3 3 3 3 3 4 4 4 4 3 2 1