Why does the console REPL parse input differently from ToExpression?

Question

In the console REPL, we can see that input is parsed in a certain way, that is not equivalent to simply calling ToExpression on the input string. From math.exe using Mathematica 13.1:

In[1]:= Print@"foo"\[NewLine]Print@"bar"
foo

In[2]:= DownValues[In][[1]]

Out[2]= HoldPattern[In[1]] :> Print["foo"]

In[3]:= ToExpression[InString[1]]
foo
bar

As we can see, the Print["bar"] is discarded when assigning In[1], but not when assigning InString[1], and calling ToExpression on InString[1] evaluates both print statements. What is the meaning of this, and is there a function analogous to ToExpression which reproduces the former behavior?

Answer 1

Input that is typed is not a string but output of InString[1] is a string.

So if you use FullForm:

In[28]:= FullForm[InString[1]]

Out[28]//FullForm= "Print@\"foo\"\\[NewLine]Print@\"bar\""

you see that the string generated by InString is a bit different than what you typed. Or more precisely it is the same but it is enclosed inside "" which original input is not.