One core, two flavors: write Osprey in C-style braces or ML-style layout with curry-by-default. Both lower to one canonical AST with typed algebraic effects, fibers, persistent collections, Hindley-Milner inference, and LLVM code generation. 2026-07-23T00:00:00.000Z https://www.ospreylang.dev/ Christian Findlay https://www.ospreylang.dev/blog/2025-01-10-building-web-apis-with-pattern-matching/ 2025-01-10T00:00:00.000Z 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Learn how Osprey’s exhaustive pattern matching and algebraic data types make web API states explicit, checked, and easier to maintain as services evolve.

https://www.ospreylang.dev/blog/2025-01-15-the-memory-safe-revolution/ 2025-01-15T00:00:00.000Z 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See how memory-safe languages, immutable data, and functional concurrency address common systems vulnerabilities and support resilient software design.

https://www.ospreylang.dev/blog/2026-05-17-persistent-collections/ 2026-05-17T00:00:00.000Z 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docs/plans/collections.md%22%3Ecollections%20plan%3C/a%3E%20are%20explicitly%20deferred:%3C/p%3E%3Cul%3E%3Cli%3E%3Cstrong%3E%3Ccode%3E[head,%20...tail]%3C/code%3E%20and%20subset%20map%20patterns%3C/strong%3E%20in%20%3Ccode%3Ematch%3C/code%3E%20%E2%80%94%20requires%20grammar%20additions%20and%20a%20parser%20regeneration%20cycle.%3C/li%3E%3Cli%3E%3Cstrong%3EList%20comprehensions%3C/strong%3E%20(%3Ccode%3E[x%20*%20x%20for%20x%20in%20xs]%3C/code%3E)%20%E2%80%94%20same%20grammar%20pipeline.%3C/li%3E%3Cli%3E%3Cstrong%3ENames%20collapsing%20to%20%3Ccode%3Elength%3C/code%3E%20/%20%3Ccode%3Econtains%3C/code%3E%3C/strong%3E%20without%20a%20%3Ccode%3Elist%3C/code%3E/%3Ccode%3Emap%3C/code%3E%20prefix%20%E2%80%94%20waiting%20on%20universal%20function%20call%20syntax%20(UFCS),%20which%20is%20in%20flight.%3C/li%3E%3C/ul%3E%3Cp%3EThe%20plan%20document%20tracks%20each%20of%20these%20with%20its%20specific%20blocker.%3C/p%3E%3Ch2%20id=%22try-it%22%20tabindex=%22-1%22%3E%3Ca%20class=%22header-anchor%22%20href=%22#try-it%22%3ETry%20it%3C/a%3E%3C/h2%3E%3Cp%3EThe%20collections%20runtime%20ships%20in%20%3Ccode%3E0.2.0%3C/code%3E.%20Install%20it%20on%20macOS%20or%20Linux:%3C/p%3E%3Cpre%20class=%22language-bash%22%3E%3Ccode%20class=%22language-bash%22%3Ebrew%20%3Cspan%20class=%22token%20function%22%3Einstall%3C/span%3E%20nimblesite/tap/osprey%3C/code%3E%3C/pre%3E%3Cp%3E%E2%80%A6and%20the%20%3Ca%20href=%22/playground/%22%3Eplayground%3C/a%3E%20supports%20the%20new%20builtins%20too.%20Build%20something%20stateful%20%E2%80%94%20a%20route%20table,%20an%20event%20log,%20an%20undo%20stack%20%E2%80%94%20and%20see%20how%20the%20persistent%20semantics%20change%20the%20shape%20of%20the%20code.%3C/p%3E

Explore Osprey’s persistent List and Map, their vector-trie and HAMT internals, structural sharing, complexity, API, and current implementation tradeoffs.

https://www.ospreylang.dev/blog/2026-06-30-osprey-flavors/ 2026-06-30T00:00:00.000Z https://www.ospreylang.dev/%3Cp%3EWhen%20I%20started%20working%20on%20Osprey,%20the%20dream%20was%20%3Cem%3Ezero%20compromise%3C/em%3E.%20I%20think%20the%20biggest%20shame%20about%20the%20most%20popular%20languages%20is%20that%20they%20compromise.%20The%20language%20designers%20make%20decisions%20for%20adoption%20but%20end%20up%20watering%20down%20the%20original%20spirit%20of%20the%20language%20because%20of%20this.%20I%20didn't%20want%20this%20for%20Osprey.%20I%20wanted%20something%20else.%20I%20wanted%20the%20language%20to%20be%20exactly%20what%20I%20wanted%20it%20to%20be%20and%20to%20have%20all%20the%20performance,%20safety%20and%20elegance%20of%20the%20other%20great,%20modern%20languages.%3C/p%3E%3Cp%3EI%20found%20out%20immediately%20that%20there%20was%20a%20big%20catch%20to%20this.%20You%20cannot%20please%20everyone.%20It's%20not%20just%20about%20aesthetics.%20You%20have%20to%20make%20tradeoffs%20when%20you%20design%20syntax.%20Certain%20decisions%20push%20you%20in%20directions%20that%20have%20rippling%20effects.%20The%20most%20obvious%20decision%20is%20the%20decision%20on%20whether%20to%20use%20indentation%20or%20braces%20to%20specify%20blocks.%3C/p%3E%3Cp%3EMany%20programmers%20that%20are%20accustomed%20to%20C%20style%20languages%20like%20C#,%20Java,%20Dart%20and%20so%20on%20find%20indentation%20based%20syntax%20to%20be%20too%20uncomfortable%20to%20use.%20But,%20indentation%20based%20languages%20mean%20you%20can%20remove%20a%20lot%20of%20symbols%20and%20reduce%20visual%20noise.%20At%20the%20end%20of%20the%20day,%20it's%20cleaner%20but%20it%20also%20alienates%20a%20whole%20group%20of%20people.%20Many%20people%20wouldn't%20touch%20Osprey%20because%20it%20looks%20like%20code%20from%20another%20tribe.%3C/p%3E%3Cp%3EEvery%20language%20picks%20a%20side,%20and%20every%20side%20loses%20someone.%20Curly%20braces%20or%20significant%20whitespace.%20%3Ccode%3Efn%20add(x,%20y)%3C/code%3E%20or%20%3Ccode%3Eadd%20x%20y%3C/code%3E.%20The%20systems%20programmer%20who%20wants%20explicit%20blocks%20and%20named%20arguments,%20versus%20the%20FP%20devotee%20who%20wants%20layout%20and%20curry-by-default.%20Pick%20braces%20and%20the%20Haskell%20crowd%20wrinkles%20their%20nose;%20pick%20layout%20and%20the%20C%20crowd%20walks%20away.%20The%20syntax%20wars%20are%20real,%20and%20they%20force%20you%20into%20a%20tribe%20before%20you've%20written%20a%20line.%3C/p%3E%3Cp%3EI%20had%20encountered%20dilemmas%20several%20times%20while%20build%20Osprey%20and%20the%20answer%20was%20always%20"put%20an%20abstraction%20here".%20My%20thinking%20was%20"Can%20we%20defer%20this%20decision?%20Can%20we%20make%20this%20aspect%20of%20the%20language%20pluggable?".%20We%20shouldn't%20bake%20decisions%20into%20the%20language%20early.%20We%20should%20allow%20people%20building%20with%20Osprey%20to%20make%20their%20own%20decisions.%20And,%20in%20many%20cases,%20I%20found%20that%20leaving%20an%20abstraction%20where%20the%20develop%20could%20make%20their%20own%20call%20was%20the%20exact%20right%20decision.%3C/p%3E%3Cp%3EThen,%20I%20asked%20the%20question%20"Can%20we%20make%20the%20syntax%20pluggable?".%20Well,%20it%20turns%20out%20that%20we%20absolutely%20can%20and%20it's%20barely%20even%20a%20for%20the%20compiler.%20When%20we%20parse%20code,%20we%20convert%20the%20code%20into%20a%20Concrete%20Syntax%20Tree%20(CST).%20This%20is%20the%20first%20pass%20that%20just%20converts%20the%20code%20unprocessed%20into%20in-memory%20data.%20Then,%20that%20data%20is%20converted%20to%20an%20Abstract%20Syntax%20Tree%20(AST).%20This%20is%20the%20processed%20syntax%20that%20can%20be%20readily%20converted%20to%20code.%3C/p%3E%3Cp%3EIt%20turns%20out%20that%20we%20can%20basically%20swap%20any%20CST%20in%20front%20of%20the%20AST.%20That's%20how%20we%20get%20flavors.%20It's%20a%20powerful%20concept.%20There%20is%20nothing%20about%20any%20language%20that%20weds%20it%20to%20the%20syntax.%20The%20syntax%20is%20basically%20just%20a%20taste%20aspect%20of%20the%20language.%20So,%20I%20made%20the%20obvious%20choice%20to%20allow%20multiple%20flavor%20syntaxes%20instead%20of%20tying%20Osprey%20to%20one%20view%20of%20the%20world.%3C/p%3E%3Cp%3EOsprey's%20answer%20is%20to%20stop%20pretending%20there's%20one%20right%20answer.%20%3Cstrong%3EOne%20core.%20Two%20flavors.%20Zero%20compromise.%3C/strong%3E%3C/p%3E%3Ch2%20id=%22the-problem-syntax-forces-a-tribe%22%20tabindex=%22-1%22%3E%3Ca%20class=%22header-anchor%22%20href=%22#the-problem-syntax-forces-a-tribe%22%3EThe%20problem:%20syntax%20forces%20a%20tribe%3C/a%3E%3C/h2%3E%3Cp%3EThe%20FP-snob-versus-systems-programmer%20divide%20is%20mostly%20about%20spelling.%20The%20ideas%20%E2%80%94%20algebraic%20data%20types,%20exhaustive%20matching,%20immutability,%20effects%20%E2%80%94%20are%20not%20in%20dispute.%20What's%20in%20dispute%20is%20whether%20%3Ccode%3Edo%3C/code%3E-blocks%20should%20have%20braces,%20whether%20application%20should%20need%20parentheses,%20whether%20a%20function%20with%20two%20arguments%20is%20one%20value%20or%20two.%20These%20a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Compare Osprey’s brace-style and ML-style flavors, how both lower to one canonical AST, and which shared compiler features and limitations apply today.

https://www.ospreylang.dev/blog/2026-07-23-perceus-arc-in-osprey/ 2026-07-23T00:00:00.000Z 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Osprey ships opt-in Perceus automatic reference counting. The compiler inserts ownership operations, and the runtime reclaims values as owner counts reach zero.