new post: "norm_cast was upstreamed to Lean4"

content/2024-02-21-norm-cast.md

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+---
+title: "norm_cast was upstreamed to Lean4"
+date: 2024-02-21
+summary: I am now a contributor to Lean!
+---
+
+In 2019, I was an intern at [Matryoshka](https://matryoshka-project.github.io/)
+in Amsterdam. There, I worked with [Robert Y. Lewis](https://robertylewis.com/)
+on a tactic for the Lean prover called `norm_cast`. The goal was to reduce the
+frustration of mathematicians when working with expressions containing casts and
+coercions. This work was merged into Mathlib and even led to the writing of a
+[paper](https://arxiv.org/abs/2001.10594).
+
+Well, after a brief transit in Lean's standard library, the tactic was
+[merged](https://github.com/leanprover/lean4/pull/3322) yesterday into the core
+language!