⎕session←{
	(indented main prompt)←⍵
	unindent←{
		⎕rawio←⎕ucs ⍺⍴8
	}
	handleError←{
		0::⍺
		(task (error msg taskname))←⍵
		⎕rawio←error,' in [',(⍕task),':',taskname,']'
		_←{⎕rawio←': ', msg} IF msg≢''
		⎕rawio←⎕ucs 10
		⎕rawio←prompt
		≢prompt
	}
	handleQuad←{
		0::⍺
		data←⍵
		⎕rawio←data
		⎕rawio←⎕ucs 10
		⎕rawio←prompt
		≢prompt
	}
	handleQuoteQuad←{
		0::⍺
		data←⍵
		⎕rawio←data
		⍺
	}
	handle←{
		0::⍺
		(task (type data))←⍵
		indented←⍺
		_←indented∘unindent IF (indented>0)∧task≢main
		type≡'!': 0 handleError task data
		type≡'⎕': 0 handleQuad data 
		type≡'⍞': 0 handleQuoteQuad data
		⍵
	}
	{∇ ⍵ handle {1 ⍵}⍇⍬} indented
}&'session'⊢0 ⎕self (6⍴' ')
⎕←'Welcome to APL9'