Owner

leanprover

34 indexed repositories · View on GitHub

lean4
Lean 4 programming language and theorem prover

Lean · 9227 stars
cslib
The Lean Computer Science Library (CSLib)

Lean · 709 stars
elan
The Lean version manager

Rust · 637 stars
verso
Lean documentation authoring tool

Lean · 384 stars
vscode-lean4
VS Code extension for the Lean 4 programming language and theorem prover

TypeScript · 313 stars
theorem_proving_in_lean4
Theorem Proving in Lean 4

Lean · 272 stars
comparator

Lean · 203 stars
fp-lean
Functional Programming in Lean

Lean · 192 stars
doc-gen4
Document Generator for Lean 4

Lean · 173 stars
reference-manual
The Lean reference manual

Lean · 129 stars
lean4-cli
A Lean 4 library for configuring Command Line Interfaces and parsing command line arguments.

Lean · 120 stars
SampCert
SampCert : Verified Differential Privacy

Lean · 105 stars
reservoir
Package registry for Lean/Lake.

Vue · 50 stars
TensorLib
A verified tensor library in Lean

Lean · 49 stars
lean-eval
Comparator-based Lean formal mathematics eval

Lean · 46 stars
lean-action
GitHub action for standard CI in Lean projects

Shell · 45 stars
lean4export
Plain-text declaration export for Lean 4

Lean · 40 stars
verso-templates
Templates for getting started with Verso

Lean · 38 stars
human-eval-lean
Hand-written verified Lean solutions for the HumanEval benchmark

Lean · 31 stars
lean-beam
Claude/Codex skill and local workflow layer for efficient interaction with Lean 4 and Monte-Carlo Tree Search.

Lean · 31 stars
14 more repositories live on View on GitHub

Beginner friendly Everything

Open All

minus function in GettingToKnow/DatatypesPatterns.lean doesn't work Open

Difficulty 1/5 Under an hour Newbie friendliness 92/100

leanprover/fp-lean#301 · Opened Sep 17, 2026
Completion popup reopens after Esc in Lean files; caused by default quickSuggestionsDelay of 200 Open

bug

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

leanprover/vscode-lean4#800 · 1 comment · Opened Sep 17, 2026
`simp [...]` with a left arrow (`←`) on a simproc should error Open

bug

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

leanprover/lean4#15197 · Opened Sep 17, 2026
MULTI_THREAD=OFF build fails: std::adopt_lock_t used in thread.h without including <mutex> Open

Difficulty 2/5 1-3 hours Newbie friendliness 86/100

leanprover/lean4#15172 · 1 comment · Opened Sep 15, 2026
Axioms and Computation: is "virtual machine" still the right term? Open

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

leanprover/theorem_proving_in_lean4#233 · Opened Sep 13, 2026
Docs: lean_sync runs setup-file and builds stale imports; the daemon pins the toolchain under .beam Open

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

leanprover/lean-beam#257 · Opened Sep 12, 2026
Delaborator omits an instance binder's name when it is used only in a later binder's type Open

P-medium

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

leanprover/lean4#15037 · Opened Sep 4, 2026
Document `strong_coinduct` Open

doc-request

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

leanprover/reference-manual#937 · Opened Sep 4, 2026
Document `monotonicity_by` Open

doc-request

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

leanprover/reference-manual#936 · Opened Sep 4, 2026
`Nat.lt` docstring Open

P-low

Difficulty 1/5 Under an hour Newbie friendliness 85/100

leanprover/lean4#15014 · Opened Sep 4, 2026
Instances are always exposed Open

doc-request

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

leanprover/reference-manual#935 · Opened Sep 3, 2026
Emscripten libuv stub definitions do not match their declarations Open

P-medium

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

leanprover/lean4#14973 · 1 comment · Opened Aug 30, 2026
5.5 "effects" -> "affects" Open

Difficulty 1/5 Under an hour Newbie friendliness 95/100

leanprover/theorem_proving_in_lean4#231 · Opened Aug 29, 2026
deriving ToJson/FromJson generates ill-typed code for self-recursion in a non-first mutual member Open

Difficulty 2/5 1-3 hours Newbie friendliness 85/100

leanprover/lean4#14958 · Opened Aug 28, 2026
Tags in the manual genre have poor behavior with spaces Open

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

leanprover/verso#972 · Opened Aug 26, 2026
simp still panics with appArg!/appFn! in the non-indexed rewriting path Open

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

leanprover/lean4#14930 · 1 comment · Opened Aug 25, 2026
UnusedVariable warning in Point3D pattern matching example (depth function) 1.5.1. Pattern Matching Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

leanprover/fp-lean#298 · Opened Aug 22, 2026
`Lean.Meta.Sym.Simp.toHave` reverses dependencies when reconstructing `have` telescopes Open

bug P-medium

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

leanprover/lean4#14804 · Opened Aug 17, 2026
nit: generated folders for blog posts shorten months to single digits without zero padding Open

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

leanprover/verso-templates#29 · Opened Aug 14, 2026
missing build instructions in blog-features example Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

leanprover/verso-templates#28 · Opened Aug 14, 2026
namespaces `Nat.double` vs `_root_.Nat.double` Open

Difficulty 1/5 Under an hour Newbie friendliness 78/100

leanprover/fp-lean#296 · Opened Aug 13, 2026
`listFullBeta_cons_r` should rename to `listFullBeta_concat_r` Open

Difficulty 1/5 Under an hour Newbie friendliness 72/100

leanprover/cslib#784 · Opened Aug 9, 2026
Plus is used instead Add class Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

leanprover/fp-lean#291 · Opened Aug 2, 2026
No `.gitignore` in workspaces created by `verso-init.sh` Open

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

leanprover/verso-templates#23 · Opened Jul 17, 2026
Declaration modifiers don't mention the public visibility Open

bug

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

leanprover/reference-manual#896 · Opened Jul 15, 2026
Axioms and Classes disagree on parametricity Open

bug

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

leanprover/reference-manual#890 · Opened Jul 14, 2026
3.1.6.3 HTTP Requests Open

Difficulty 1/5 Under an hour Newbie friendliness 72/100

leanprover/fp-lean#282 · Opened Jul 13, 2026
Document interaction of `namespace` and `open` Open

doc-request

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

leanprover/reference-manual#884 · Opened Jul 8, 2026
`lambdaMetaTelescope` doesn't preserve binder names Open

bug P-low

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

leanprover/lean4#14264 · 1 reaction · Opened Jul 3, 2026
Vscode-server processes are not being killed Open

bug

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

leanprover/lean-workbench#54 · Opened Jul 2, 2026
Invalid link to tests in 12.4.3 Open

Difficulty 1/5 Under an hour Newbie friendliness 88/100

leanprover/reference-manual#878 · Opened Jun 28, 2026
`"&"` in docstring of `Html.text` is not rendered literally Open

Difficulty 1/5 Under an hour Newbie friendliness 82/100

leanprover/verso#898 · Opened Jun 28, 2026
Automatically generated tags for headings are not deduplicated Open

Difficulty 2/5 1-3 hours Newbie friendliness 85/100

leanprover/verso#897 · Opened Jun 28, 2026
Static facets and Export.Parse not built Open

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

leanprover/lean4export#40 · 6 comments · Opened Jun 25, 2026
Rendering issue with space after `#check` Open

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

leanprover/verso-slides#52 · Opened Jun 19, 2026
Chapter 8.8 Dependent Pattern Matching claims `Vect.tail` needs an auxiliary function Open

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

leanprover/theorem_proving_in_lean4#222 · Opened Jun 7, 2026
perf: hoist row pointers in setupPhase1/setupPhase2 Open

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

leanprover/lp-backend-pure#16 · 1 comment · Opened Jun 4, 2026
Document `#guard` Open

doc-request

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

leanprover/reference-manual#853 · Opened May 24, 2026
§8.3.3 Exercises asks me to implement ForM using `for … in` in the wrong monad Open

Difficulty 1/5 Under an hour Newbie friendliness 78/100

leanprover/fp-lean#274 · Opened May 8, 2026
Suggestion: provide FP detail in Chapter 3.4 description of `suffices` Open

Difficulty 1/5 1-3 hours Newbie friendliness 78/100

leanprover/theorem_proving_in_lean4#219 · Opened May 5, 2026
[Typo] 7.2.2. A Universe of Finite Types: typo in Finite.enumerate .pair explanation Open

Typo

Difficulty 1/5 Under an hour Newbie friendliness 90/100

leanprover/fp-lean#269 · Opened Apr 11, 2026
Minor typo in delaborator section Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

leanprover/reference-manual#828 · Opened Apr 10, 2026
RFC: expand reducibility warning about class-typed `def`s Open

P-medium RFC

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

leanprover/lean4#13351 · Opened Apr 9, 2026
Chapter 8.6 Functional Induction - unnecessary `simp [ack, *]` Open

Difficulty 1/5 Under an hour Newbie friendliness 82/100

leanprover/theorem_proving_in_lean4#218 · 1 reaction · Opened Apr 5, 2026
Link from "extended field notation" to "generalized field notation" Open

doc-request

Difficulty 1/5 Under an hour Newbie friendliness 78/100

leanprover/reference-manual#815 · Opened Mar 25, 2026
Add Explicit Reference to Definition of `idahospiders` in 3.5.6 Append Example Open

Difficulty 1/5 Under an hour Newbie friendliness 75/100

leanprover/fp-lean#262 · Opened Jan 26, 2026
Chapter 8.6 Functional Induction - simp ack is unsued Open

Difficulty 1/5 Under an hour Newbie friendliness 68/100

leanprover/theorem_proving_in_lean4#215 · Opened Jan 26, 2026
Axioms and Computation: Incorrect definition of linv and consequently proof of linv_comp_self Open

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

leanprover/theorem_proving_in_lean4#214 · Opened Jan 5, 2026
In §1.3.2.1 (“Messages You May Meet”) Open

Difficulty 1/5 Under an hour Newbie friendliness 68/100

leanprover/fp-lean#254 · Opened Dec 22, 2025
[Typo] 6.11. Using the Library: name of theorem -> name of the theorem Open

Difficulty 1/5 Under an hour Newbie friendliness 92/100

leanprover/theorem_proving_in_lean4#206 · Opened Dec 5, 2025

leanprover

Get new issues in your inbox