We have been using functional programming here at S&P Capital IQ in Scala, Haskell, and our homegrown reporting language Ermine, since 2008. We'll spotlight two of the projects we've worked on in the past five years and cover the challenges that drove us to write our own programming language. The first project we'll cover is our portfolio analytics (PA) engine, used on capitaliq.com for performance and risk attribution and in ClariFI, a quant-focused desktop product. The engine evaluates jobs consisting of batches of PA calculations, which we represent monoidally and optimize to process in a streaming fashion using a minimal number of passes over input data. The second is how we've used Scala and Haskell in a multi-year project to build a general purpose reporting and visualization framework for constructing useful views and reports from CapitalIQ datasets. That framework consists of several components, the most novel of which is a Haskell-like programming language with row types, called Ermine, designed for working with and manipulating relational data. Upon Ermine we have layered a combinator library for building interactive reports and visualizations from these data. These reports are abstract descriptions of layout, with pointers to the data, and we've written several interpreters for this DSL to export to a variety of formats: a report can be rendered as an interactive HTML+JS page, a Java FX UI, or exported to PDF or Excel from a simple declarative specification. Along the way we've had to face many challenges including interoperating with the web and the JVM, getting monadic code in scala to scale, fostering adoption in a predominantly imperative workplace, and selling management on a custom programming language.
discovered Haskell in 2006 after many years of writing compilers for toy imperative languages that somehow all looked like a mishmash of Perl, Python and C++. Upon realizing the error of his ways and after briefly flirting with dependent and substructural type systems he switched to Haskell and ever since has sought to make up for his past crimes by giving back to the community. He currently maintains more Haskell packages than anyone, sits on the haskell.org committee, chairs the Haskell core libraries committee, organizes Boston Haskell, has managed the Google Summer of Code for the Haskell community for the last 4 years and doesn't get to sleep much.