SML-Handbook - SML version of code for John Harrison's "Handbook of Practical Logic and Automated Reasoning" (Chapter 6 on Interactive Theorem Proving only)
For Isabelle, Moscow ML, Standard ML of New Jersey and Poly/ML.
New entry in the Archive of Formal Proofs: https://www.isa-afp.org/entries/FOL_Harrison.shtml
The verification in Isabelle of the kernel is described here:
Alexander Birch Jensen, Anders Schlichtkrull, Jørgen Villadsen: Verification of an LCF-Style First-Order Prover with Equality. Isabelle Workshop 2016: http://www21.in.tum.de/~nipkow/Isabelle2016/
Please provide feedback to Associate Professor Jørgen Villadsen, DTU Compute, Denmark: http://people.compute.dtu.dk/jovi/