When somebody uses the word 'natural'

When I can no longer tell whether my implementation is faithful to the semantics or not

When I read a blog post by Robert Harper

When everybody hypes a language that I find crap

When a new language doesn't get lexical scope right

When I heard of Dart's type system

When I hear they're adding features to C++

When I finally grokked delimited continuations

(thanks to the example in A Monadic Framework)

When it comes to my mind that the 1990s project of moving OSes to dynlangs failed and now we're all using Unix

When I'm about to replace an important subsystem in my VM

When somebody says 'but Clojure will bring more people to Lisp'

When I see that Ruby's parser is 10,000 lines of C

When somebody tries to explain JavaScript's prototype system

When I see that a new language makes a difference between statements and expressions

When I mention first-class environments and fexprs to an academic Schemer

When I try to structure data in Scheme

When a language designer talks about their ideas of improving the rules of lexical scope

When a code base uses a directory structure deeper than one level

When I read about Perl 6 semantics

When I try to design an extension or alternative to S-expressions

When I see that the designer of a new dynlang knows the CLHS and RnRS by heart

When somebody asks me how I added a DSL to my Lisp program in 3 minutes

When somebody says he doesn't like exceptions because he likes to handle errors where they appear

(This is the first post of a new series called "This PLT Life", inspired by This Advertising Life.)