[emilprogviz]

I've always felt the same, so I recently made an interactive mock-up of such an IDE feature: https://emilprogviz.com/expand-calls/?inline,substitution Not mobile friendly, best seen on desktop. To inline a function call, either click the "+" icon, or go up/down with the keyboard and press spacebar when the caret is on that line.

(There's also a video where I explain the reasoning behind the mock-up, but I guess the motivation is already blatantly obvious to most readers of the above discussion, so feel free to skip the first chapters: https://youtu.be/wdf6S6oumH8 )

Then I learned that the Smalltalk editor Pharo has a similar feature! Seems many people have the same idea. Today's major IDE makers should have copied this feature already!