# F*

17 Hacker News commenters recommended F* and 3 criticized it, November 2025 to November 2026. It was recommended in 7 of 13 months. It meets the Hacker Approved badge rule.

**Verdict:** People recommend it for proof-oriented programming with a powerful type system and real-world verified code. Critics say it can be slow and hard to use for complex software.

## Why people recommend it

- Software-focused alternative to Lean and Isabelle (4 comments): "proof-oriented alternative to Isabelle that is focused on software verification" ([source](https://news.ycombinator.com/item?id=47069085)) "a much better choice for proof-oriented programming than lean4" ([source](https://news.ycombinator.com/item?id=47752121)) "competes directly with Lean but is more guided towards SWE" ([source](https://news.ycombinator.com/item?id=47928558))
- Familiar syntax, similar to F# (3 comments): "I don't find F* syntax anymore intimidating than Haskell, Scala, Mercury, Prolog, etc." ([source](https://news.ycombinator.com/item?id=49148720)) "F# for high-level, and F* Low* for theorem proving and low-level coding" ([source](https://news.ycombinator.com/item?id=47752773)) "F* looks a lot like F# code with semantics you should be familiar with" ([source](https://news.ycombinator.com/item?id=49147697))
- Used in real-world and embedded verification (2 comments): "F* is being used on embedded and in other realworld apps where formal verification is necessary or highly advantageous" ([source](https://news.ycombinator.com/item?id=46048892)) "They actually wrote a whole verified TLS implementation in F*" ([source](https://news.ycombinator.com/item?id=49149447))
- Powerful type system, expressive semantics (2 comments): "the metatheory is also expressive enough that your source language can be pretty wild with your denotational semantics" ([source](https://news.ycombinator.com/item?id=49151377)) "It has a very powerful type system" ([source](https://news.ycombinator.com/item?id=46292118))

## What people warn about

- Slow and hard for complex software (2 comments): "trade off a lot of performance to the point that it makes them practically unusable" ([source](https://news.ycombinator.com/item?id=49756683)) "They're really not fun to try and make complex software with" ([source](https://news.ycombinator.com/item?id=47753534))

## Alternatives hackers recommend

- [SPARK Ada](https://hackerapproved.com/p/spark.md): 63 recommend
- [Dafny](https://hackerapproved.com/p/dafny.md): 24 recommend
- [Verus](https://hackerapproved.com/p/verus.md): 23 recommend

## Cite as

Hacker Approved, "F*", https://hackerapproved.com/p/f/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).