Conal Elliott asks: What resources & practices would you recommend for helping a group of Java & C++ programmers learn to work in Haskell? I saw the question first on Twitter, but my compression skills were not up to the task of answering there.
I have two recommendations: teach them the simplest definitions of the fundamentals; read programs with them, out loud, like children's books, skipping nothing.
These steps are often passed hurriedly, by teachers so steeped in a subject they don't realize how different their worlds are, by students eager to build things as quickly in a new programming language as they do in the old. Most likely, the students will assume that they just need to learn new syntax to be off and running. Indeed, I am sure they are capable, self-motivated software professionals and that they would succeed in learning Haskell, just without the deeper understanding that can make it such a joy.
As a test, ask your students to write down the definition of 'type'. I'll bet that their answers will be longer than 'set' and include some mention of bytes, words and big-endian. We were all trained to be mechanics instead of drivers, because all we had were go-carts.
C and its children will have left clutter in their minds. Types will be obstacles, efficiency a drug, correctness assured by machismo. They will gloss over code without really reading it, trying to fit it into an existing model. Saying things out loud helps slow things down, forces them to make connections between symbols, words and definitions so fundamental they are rarely written down. (I backtracked through Paul Hudak's book for hours trying to find out how to say '::'; newcomers ask pretty regularly in #haskell.)
Make sure they know all the places that patterns can appear in code and how they work. Make sure they know that data constructors are functions. Have them verify that with :type in GHCi. And that type constructors are functions, verifying with :kind. They should be familiar with the syntax and semantics of higher-order types before they meet IO, so that they understand it is not magic.
Lists, recursion, functional algorithms, none of these will be challenges, but constructs they have not seen before will give them much more trouble if they cannot deconstruct them to primitives. I cannot imagine Conal omitting such fundamental semantics from his lessons, but I can easily imagine both teacher and students, excited to build new stuff, skimping on the exercises necessary to flush out the old foundations and cement the new.
I have two recommendations: teach them the simplest definitions of the fundamentals; read programs with them, out loud, like children's books, skipping nothing.
These steps are often passed hurriedly, by teachers so steeped in a subject they don't realize how different their worlds are, by students eager to build things as quickly in a new programming language as they do in the old. Most likely, the students will assume that they just need to learn new syntax to be off and running. Indeed, I am sure they are capable, self-motivated software professionals and that they would succeed in learning Haskell, just without the deeper understanding that can make it such a joy.
As a test, ask your students to write down the definition of 'type'. I'll bet that their answers will be longer than 'set' and include some mention of bytes, words and big-endian. We were all trained to be mechanics instead of drivers, because all we had were go-carts.
C and its children will have left clutter in their minds. Types will be obstacles, efficiency a drug, correctness assured by machismo. They will gloss over code without really reading it, trying to fit it into an existing model. Saying things out loud helps slow things down, forces them to make connections between symbols, words and definitions so fundamental they are rarely written down. (I backtracked through Paul Hudak's book for hours trying to find out how to say '::'; newcomers ask pretty regularly in #haskell.)
Make sure they know all the places that patterns can appear in code and how they work. Make sure they know that data constructors are functions. Have them verify that with :type in GHCi. And that type constructors are functions, verifying with :kind. They should be familiar with the syntax and semantics of higher-order types before they meet IO, so that they understand it is not magic.
Lists, recursion, functional algorithms, none of these will be challenges, but constructs they have not seen before will give them much more trouble if they cannot deconstruct them to primitives. I cannot imagine Conal omitting such fundamental semantics from his lessons, but I can easily imagine both teacher and students, excited to build new stuff, skimping on the exercises necessary to flush out the old foundations and cement the new.
