Background

REPL should output the evaluated value of the latest input.
But tmplscript REPL required the whole input since interactive mode starts so that it can refer pre-defined variables.
For that reason, it read whole input and put only the output difference with the previous one (outStr[previousOutLen:]).

Problem

When non-idempotent functions are used, output length differs in each evaluation.
Diff algorithm above works wrongly and sometimes causes index out of range.

tmpl:12> {{range until (randInt 1 10)}}{{println .}}{{end}}
7
8

0

0
1
2
3
4
5
6

tmpl:13> {{range until (randInt 1 10)}}{{println .}}{{end}}
panic: runtime error: slice bounds out of range [156:155]

goroutine 1 [running]:
main.runREPLMode(0xc00003e5c0)
        C:/Users/tanot/OneDrive/Documents/tmplscript/main.go:107 +0x53d
main.main()
        C:/Users/tanot/OneDrive/Documents/tmplscript/main.go:26 +0x437

Solution

Instead, separation character is introduced to detect output diff.
It inserts non-printable character "\x034" before parsing and shows output only after "\x034".