Folding over fields
One of the best features of ML is pattern matching. Pattern matching is essentially a way of writing a case analysis driven by the structure...
The dangers of being too partial
This article deals with some not well-known dark corners of the OCaml compiler and how to get around them to produce more efficient code. The...
By: Pascal Zimmer
Ensuring that a function is polymorphic
Here’s a little trick that I find useful when I get a type error due to a function that I believe is polymorphic, but isn’t...
By: Stephen Weeks
Core Principles: uniformity of interface
This is intended to be the first in a series of posts talking about the design principles behind core, Jane Street’s alternative to OCaml’s standard...
By: Yaron Minsky
Core has landed
We are proud to announce the first public release of `core`, Jane Street's own alternative to OCaml's standard library. We use this library as the...
By: Yaron Minsky
using with type on a variant type
Here’s a type-checking problem I ran into today. I had a module with a variant type matching a signature that exposed the variant type.
By: Stephen Weeks
OCaml Annoyance #23: type declarations are implicitly recursive
Unlike let declarations, type declarations in OCaml are automatically recursive. This seems harmless at first, but it actually causes more trouble than it’s worth. To...
By: Yaron Minsky
The ML sweet spot
I just got back from visiting Northeastern and Harvard where I yet again flogged a version of my POPL talk. Olin Shivers was my host...
By: Yaron Minsky
Bind without tears
One of the annoyances of using monads in OCaml is that the syntax is awkward. You can see why if you look at a simple...
By: Yaron Minsky
Variable-argument functions
Here’s another puzzle:
By: Stephen Weeks
Typing RPCs
At Jane Street, we end up writing lots of messaging protocols, and many of these protocols end up being simple RPC-style protocols, *i.e.*, protocols with...
By: Yaron Minsky
Using let module for matching
In OCaml, referring to constructors defined in other modules can be somewhat awkward. Suppose we have a module like the following.
By: Stephen Weeks
Extracting an exception from a module
The Unix module defines the Unix_error exception constructor.
By: Stephen Weeks
A universal type?
Is it possible in OCaml to implement a universal type, into which any other type can be embedded? More concretely, is possible to implement the...
By: Stephen Weeks
Talking at Penn
I just got back from an enjoyable visit at Penn. I gave a version of my POPL talk for an audience consisting in large part...
By: Yaron Minsky
We've got a blog!
Jane Street finally has a blog! Jane Street is one of the biggest commercial users of OCaml, and we like to think that we’ve picked...
By: Yaron Minsky
HOWTO: Static access control using phantom types
We thought that phantom types would be an appropriate topic for our first real post because they are a good example of a powerful and...
By: Yaron Minsky
