--- title: Algorithms & Combinators - Conor Hoekstra - NDC Toronto 2026 description: A conference talk exploring algorithm families (copy, map, chunk) through the lens of argument types and combinators. The speaker demonstrates how algorithms... canonical: https://daily.dev/posts/algorithms-combinators---conor-hoekstra---ndc-toronto-2026-34qgndddg twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Algorithms & Combinators - Conor Hoekstra - NDC Toronto 2026 | daily.dev og:description: A conference talk exploring algorithm families (copy, map, chunk) through the lens of argument types and combinators. The speaker demonstrates how algorithms... og:url: https://daily.dev/posts/algorithms-combinators---conor-hoekstra---ndc-toronto-2026-34qgndddg og:image: https://api.daily.dev/og/posts/34qGNdddG.png og:image:alt: Algorithms & Combinators - Conor Hoekstra - NDC Toronto 2026 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Algorithms & Combinators - Conor Hoekstra - NDC Toronto 2026 **[NDC Conferences](https://daily.dev/sources/ndc)** · 56 min read · 0 upvotes · 0 comments ## Summary A conference talk exploring algorithm families (copy, map, chunk) through the lens of argument types and combinators. The speaker demonstrates how algorithms like filter, map, and chunk-by are really flavors of the same underlying operation, differing only in whether they take an integer, boolean mask, unary predicate, or binary predicate. Using array languages (APL, BQN, TinyAPL) as a live coding environment, the talk shows how combinators like C (flip), W (duplicate), S, Sigma, and Psi appear across languages including C++ and Python. Key insights include: filter and copy_if are the same algorithm; C++ unique is really an adjacent filter; C++ range projections are equivalent to the Psi combinator; and chunk, chunk_by, and chunk_by_key form a family analogous to the copy family. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is the difference between C++'s std::unique and the concept of an adjacent filter? std::unique in C++ actually implements what could be called an adjacent filter: by default it removes adjacent equal elements, using a binary operation applied to neighboring items, but that binary operation can be overloaded with anything, not just equality. The name 'unique' only reflects the 90% common use case; the underlying capability is removing elements based on any binary predicate applied to adjacent pairs, a semantic borrowed from range-v3's adjacent_filter. _Developers puzzling over unusual std::unique behavior can compare implementation notes like this on daily.dev._ ### What does the C++23 adjacent_transform algorithm do and why was it renamed from adjacent_difference? C++23's adjacent_transform applies a binary operation to adjacent elements in a sequence, generalizing C++98's adjacent_difference, which hardcoded subtraction into its name. Because the binary operation can be swapped for anything, such as addition to compute Fibonacci-like sequences, naming the algorithm after its default operation (difference) was misleading, so it was renamed to reflect the general transform behavior instead. _Teams migrating C++ codebases to newer standards can track naming and behavior changes like this on daily.dev._ ### What is the SI (Σ-like) combinator and how does it relate to projections in C++20 ranges? The SI combinator takes a unary operation and a binary operation and returns a binary operation that applies the unary operation to both arguments before applying the binary operation, useful for patterns like comparing sizes instead of values directly. C++20 ranges projections (used with sort, for example) are effectively an alternative spelling of this same combinator, letting you pass a unary function like size to change what property the binary comparator inspects. _Developers designing custom comparators or projections in C++ ranges can dig into patterns like this on daily.dev._ ## Similar posts on daily.dev - [What are your programming "hunches" you haven't yet investigated?](https://daily.dev/posts/what-are-your-programming-hunches-you-haven-t-yet-investigated--ye8oavk2s) · Lobsters · 1 upvotes · 0 comments - [Scalar 2026: Celebrating Functional Programming Fiesta](https://daily.dev/posts/scalar-2026-celebrating-functional-programming-fiesta-wcetkdfrl) · SoftwareMill · 0 upvotes · 0 comments - [Combinators](https://daily.dev/posts/combinators-4ttthuwqu) · Hacker News · 0 upvotes · 0 comments --- Tags: [#algorithms](https://daily.dev/tags/algorithms), [#c++](https://daily.dev/tags/c++), [#functional-programming](https://daily.dev/tags/functional-programming) [View this post on daily.dev](https://daily.dev/posts/algorithms-combinators---conor-hoekstra---ndc-toronto-2026-34qgndddg) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Algorithms & Combinators - Conor Hoekstra - NDC Toronto 2026","url":"https://daily.dev/posts/algorithms-combinators---conor-hoekstra---ndc-toronto-2026-34qgndddg","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/algorithms-combinators---conor-hoekstra---ndc-toronto-2026-34qgndddg"},"datePublished":"2026-07-20T13:19:23.003Z","dateModified":"2026-09-13T21:18:44.255Z","description":"A conference talk exploring algorithm families (copy, map, chunk) through the lens of argument types and combinators. 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