--- title: Seeing types where others don't | daily.dev description: A developer documents their multi-year journey building a static type inference system for jq, the JSON processing tool. The post explains why jq's error... canonical: https://daily.dev/posts/seeing-types-where-others-don-t-7srbyqoa7 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Seeing types where others don't | daily.dev og:description: A developer documents their multi-year journey building a static type inference system for jq, the JSON processing tool. The post explains why jq's error... og:url: https://daily.dev/posts/seeing-types-where-others-don-t-7srbyqoa7 og:image: https://api.daily.dev/og/posts/7SRbYQoA7.png og:image:alt: Seeing types where others don't 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. # Seeing types where others don't **[Lobsters](https://daily.dev/sources/lobsters)** · 18 min read · 0 upvotes · 0 comments ## Summary A developer documents their multi-year journey building a static type inference system for jq, the JSON processing tool. The post explains why jq's error messages are poor (no value provenance tracking), then walks through progressively more sophisticated approaches to inferring types from jq programs: starting with shape inference from field accesses, then adding type variables with constraint accumulation, and finally moving to a constraint-solver-based approach. Along the way, the author explores intersection types, overloaded operators, and the challenges of jq's stream semantics. The work-in-progress tool is called tjq and is available on GitHub. The broader takeaway is that even dynamically typed languages have implicit types, and we could leverage static inference to produce better error messages without requiring explicit annotations. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Type inference has usability problems \(2019\)](https://daily.dev/posts/type-inference-has-usability-problems-2019--gfzh59908) · Lobsters · 4 upvotes · 0 comments - [Haskell for all: Record type inference for dummies](https://daily.dev/posts/haskell-for-all-record-type-inference-for-dummies-wub8q2glx) · Planet Haskell · 0 upvotes · 0 comments - [Visual Types](https://daily.dev/posts/visual-types-yqneyg40x) · Lobsters · 5 upvotes · 0 comments --- Tags: [#bash](https://daily.dev/tags/bash), [#general-programming](https://daily.dev/tags/general-programming), [#rust](https://daily.dev/tags/rust), [#type-systems](https://daily.dev/tags/type-systems) [View this post on daily.dev](https://daily.dev/posts/seeing-types-where-others-don-t-7srbyqoa7) ```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":"Seeing types where others don't","url":"https://daily.dev/posts/seeing-types-where-others-don-t-7srbyqoa7","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/seeing-types-where-others-don-t-7srbyqoa7"},"datePublished":"2026-03-18T20:59:17.206Z","dateModified":"2026-10-15T02:17:51.943Z","description":"A developer documents their multi-year journey building a static type inference system for jq, the JSON processing tool. 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