Issue 12 2016-07-21

• What Template Haskell gets wrong and Racket gets right

  Why are macros in Haskell terrible, but macros in Racket great?

• Optionally Exposed

  A build tool giving me a transitive dependency on text only so that the instance you defined compiles is pointless.

• Algebraic patterns: Semigroup

  A Semigroup is a data type together with a method of composition satisfying the associativity rule.

• Rank ’n Classy Limited Effects

  Applications, then, are just an environment comonad of monad morphisms. More plainly, they’re a record of effect interpreters.

• Destroy All Ifs: A Perspective from Functional Programming

  By replacing conditionals with lambdas, we can invert control and make our code both easier to reason about and more generic.

• Typeclasses and Run-Time Dependency Management

  But what we need is a run-time error, not a compile-time one. (This is one of the rare cases you’ll hear a Haskeller saying this.)