[mannyv]

Apple's MPW was Apple's programming environment for a long time.

It's been a while, but I believe that it represented everything in a tree of n-character chunks (n = 6?). It was probably the first editor that I used that could open files of pretty much any length.

[eschneider]

I do miss the 'select and execute', and 'everything is a shell' model of MPW. Definitely one of my favorite development environments.

[scelerat]

elsewhere on HN today is a short article on BBedit, which has a really nice shell worksheet interface similar to the old MPW. Select the text you want to execute, hit control-return, and the shell output will appear below the selected text.

[kerkeslager]

If I'm not mistaken, I believe this feature originates with Smalltalk (you might think that Smalltalk is a language and the feature in question is an editor feature, but most Smalltalk variants are tightly integrated with an editing environment).

[tomjakubowski]

sounds like plan9's acme