[panic]

I reduced the need for escaping further by having a backslash escape a whole series of backslashes rather than just the very next character.

How do you write the string with characters '\' and ']'? It seems like the natural way to write it, [\\\]], would end up being lexed as [\\\] (a string with two backslashes) followed by an unmatched string end character ']'.

[akkartik]

It's just [\\]]. "\\]" is an escape for "\]".

[yorwba]

I took this as an opportunity to finally try out mu. Very readable code!

Is there a way to write a string that ends with a backslash? The way `slurp_one_past_backslashes` is used seems to make that impossible.

EDIT: I thought typing a literal 0 byte might work, but apparently mu uses a different mechanism to delimit strings in memory.

[akkartik]

To clarify my comment from last night: the following code[1]:

  x:address:array:char <- new [abc]

would look like this in memory, assuming the allocator returned address 1000 as the value of x:

  1000: 3
  1001: 97  # a
  1002: 98  # b
  1003: 99  # c

That's it. There's no trailing null character. Address 1004 is not part of this allocation.

The length of the array cannot be modified, only read (using instruction length). If we need a larger array we must allocate new and copy over, just like in C.

The elements of an array can be read and written using instructions index and put-index, respectively. Here's a fragment of code to make the final character of x a backslash:

  len:num <- length *x
  last:num <- subtract len, 1
  put-index *x, last, 92  # ascii code for backslash

[1] The verbose "address:array:char" (read as "address to an array of characters") is typically abbreviated as "text" in Mu programs. I've written out the full type to make things more explicit.

[akkartik]

Ah, you're right! Trailing backslashes can't be represented. I need to rethink this.

If you want to construct it from scratch, strings and arrays in general are prefixed with their length. put-index on the final index would be the workaround.