Feature suggestion: REPL mode

[axsk]

I love how chain allow so much REPL work to be expressed as one-liners :)

However, most of the time I start with an expression (without @chain) and then want to add onto this.
This usually means going to the beginning, inserting @chain and then back to the end continuining the ammended expressions.

Ideally my REPL would just live in @chain all of the time :)
Could we have a @chain REPL mode, where all space seperated expressions are automatically chained?

Could this lead to any problems (function definitions, blocks, ...?)