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.
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...
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...
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...
Variable-argument functions
Here’s another puzzle:
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...
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.
Extracting an exception from a module
The Unix module defines the Unix_error exception constructor.
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...
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...
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...
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...
