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ucsd-progsys

2 indexed repositories · View on GitHub

liquidhaskell
Liquid Types For Haskell

Haskell · 1334 stars
liquid-fixpoint
Horn Clause Constraint Solving for Liquid Types

Haskell · 166 stars

Beginner friendly Everything

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{-@ data ... @-} refinements on a Haskell newtype are accepted and used, but are unchecked at construction Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

ucsd-progsys/liquidhaskell#2766 · 1 comment · Opened Sep 17, 2026
Inconsistent results with seemingly irrelevant change Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ucsd-progsys/liquid-fixpoint#855 · 1 comment · Opened Sep 9, 2026
LH requires redundant evidence in scope of type-nat indexed data types Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2751 · Opened Aug 28, 2026
Missing support for type-nat constants in refinement types Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

ucsd-progsys/liquidhaskell#2750 · Opened Aug 28, 2026
`--typeclass` panics on type-nat indexed data types Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2749 · Opened Aug 28, 2026
Missing constraints in specs should be reported like GHC's "No instance" errors Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

ucsd-progsys/liquidhaskell#2745 · Opened Aug 20, 2026
Typeclasses are only lifted to the logic if at least one method has a spec Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2744 · Opened Aug 20, 2026
Instances of embedded classes are assumed canonical and cannot be verified Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2743 · Opened Aug 20, 2026
Rename infix mod and / Open

Difficulty 4/5 3-5 days Newbie friendliness 64/100

ucsd-progsys/liquidhaskell#2735 · 1 reaction · Opened Aug 9, 2026
Using `$` without `--etabeta` flag may break otherwise correct terms Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2730 · Opened Jul 30, 2026
Proof combinators fail under type-level constrained data types Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2729 · Opened Jul 30, 2026
Higher-kinded class parameters are elaborated with wrong kind Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2727 · Opened Jul 29, 2026
Unsoundness bug: Refinements on lambdas over GADT-existential type variables are checked under an inconsistent environment; SAFE program crashes Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2725 · 4 comments · Opened Jul 26, 2026
aeson-derived instances (`deriving anyclass FromJSON/ToJSON`) make the whole module's environment inconsistent — every spec verifies vacuously ("Found false") Open

Difficulty 4/5 3-5 days Newbie friendliness 42/100

ucsd-progsys/liquidhaskell#2718 · 1 comment · Opened Jul 18, 2026
Liquid Haskell ignores let definitions with no name binding Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2714 · Opened Jul 3, 2026
Failure to instantiate type variable Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2710 · 4 comments · Opened Jun 19, 2026
PLE does not discover equality with partial application Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2707 · 1 comment · Opened Jun 11, 2026
Binders are picked only from the first equation of a definition Open

Difficulty 5/5 Over a week Newbie friendliness 38/100

ucsd-progsys/liquidhaskell#2704 · 1 comment · Opened Jun 10, 2026
Check failures in Functor and Monad methods Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2703 · Opened Jun 10, 2026
"LH can't be run with Haddock" with LH plugin in VS Codium Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

ucsd-progsys/liquidhaskell#2697 · 10 comments · Opened Jun 5, 2026
splitc unexpected when working with NonEmpty Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

ucsd-progsys/liquidhaskell#2692 · 13 comments · Opened May 31, 2026
Seemly different functions proved as equal Open

Difficulty 4/5 3-5 days Newbie friendliness 42/100

ucsd-progsys/liquidhaskell#2653 · 14 comments · Opened Apr 16, 2026
Document limitations of liquid haskell Open

Difficulty 2/5 1-3 hours Newbie friendliness 62/100

ucsd-progsys/liquidhaskell#2647 · 1 comment · Opened Mar 23, 2026
Liquid fix-point doesn't compile Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquid-fixpoint#829 · 1 comment · Opened Mar 17, 2026
Ugly error message signals optimization opportunities for abstract predicates Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2638 · Opened Mar 16, 2026
Use droplet icon with this repo? Open

Difficulty 1/5 Under an hour Newbie friendliness 25/100

ucsd-progsys/liquidhaskell#2635 · 1 comment · Opened Mar 14, 2026
"--reflection" crashes with `OverloadedRecordDot` Open

classes

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2630 · 2 comments · Opened Mar 12, 2026
"--reflection" crashes with unpacked strict fields Open

Difficulty 4/5 3-5 days Newbie friendliness 46/100

ucsd-progsys/liquidhaskell#2629 · 10 comments · Opened Mar 12, 2026
Name resolution chockes on depednent functions Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2626 · 9 comments · Opened Mar 9, 2026
fixpoint --version doesn't show the correct commit hash Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ucsd-progsys/liquid-fixpoint#817 · Opened Dec 19, 2025
Investigate unresponsive queries of z3 in Lists.hs Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2599 · Opened Dec 17, 2025
Uniquifying kvars introduces out-of-scope names Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

ucsd-progsys/liquid-fixpoint#800 · 4 comments · Opened Nov 20, 2025
Odd rendering of ADT with Map Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquid-fixpoint#785 · 1 comment · Opened Nov 2, 2025
Implement lint checks on the input constraints Open

good first issue

Difficulty 3/5 1-2 days Newbie friendliness 42/100

ucsd-progsys/liquid-fixpoint#783 · 1 comment · Opened Oct 31, 2025
Why do we need inline, measure, and reflection? Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2584 · 2 comments · Opened Oct 31, 2025
Reflection doesn't behave as measures Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ucsd-progsys/liquidhaskell#2582 · 12 comments · Opened Oct 30, 2025
Reflection weakens higher order reasoning Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2579 · 3 comments · Opened Oct 28, 2025
Data Constructors in Higher Order Positions Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2573 · 3 comments · 1 reaction · Opened Sep 26, 2025
liquid-fixpoint tests fail when run from hackage Open

good first issue

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ucsd-progsys/liquid-fixpoint#760 · 8 comments · 1 reaction · Opened Aug 14, 2025
`--cores` flag is detrimental to performance Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2562 · 9 comments · Opened Jul 27, 2025
Cannot make a Storable instance Open

Difficulty 4/5 3-5 days Newbie friendliness 30/100

ucsd-progsys/liquidhaskell#2556 · 15 comments · Opened Jul 11, 2025
Cannot prove termination of mutual structural recursion Open

termination

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2552 · 2 comments · Opened Jun 8, 2025
Liquid Haskell should accept `UnicodeSyntax` Open

good first issue

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2551 · 4 comments · Opened Jun 8, 2025
Make the plugin aware of annotation changes in its dependencies Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2546 · Opened May 26, 2025
Puzzling constraint for dependent pairs Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2536 · 1 comment · Opened May 19, 2025
Use theory of arrays to reason with operations of Data.Map Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

ucsd-progsys/liquidhaskell#2534 · 14 comments · Opened May 16, 2025
Measure with Nat result lets LiquidHaskell go panic Open

Difficulty 3/5 1-2 days Newbie friendliness 38/100

ucsd-progsys/liquidhaskell#2528 · Opened May 8, 2025
Local constraints in type class definitions Open

classes

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ucsd-progsys/liquidhaskell#2527 · Opened May 8, 2025
Convert a method to logic language Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

ucsd-progsys/liquidhaskell#2526 · 1 comment · Opened May 7, 2025
Nonnegativity predicate in Integral class Open

classes

Difficulty 5/5 Over a week Newbie friendliness 30/100

ucsd-progsys/liquidhaskell#2525 · 1 comment · Opened May 7, 2025

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