C Shell for Windows 1.0.8.4

What's new in 1.0.8.4

The theme of this release is silent success — the shell accepting something,
reporting 0, and doing something other than what was asked. An alias that did
nothing. An unterminated if that ran its body. A $dir/$file that came out as
$dir. A -n that was accepted and ignored, so a syntax check *ran* the script.
A --help that hung. Most of what follows is one of those.

245 built-in commands; 159 test suites.

⚠️ Behaviour change: == and != compare text

This is the one most likely to change what an existing script does, so it is
first.

In csh, == and != compare strings; <, >, <= and >= compare
numbers. That split is the whole of the language's type system. cshw
honoured the second half and not the first: it tried a numeric comparison
first whenever both operands looked like numbers. Measured against tcsh
6.24.13, every one of these disagreed:

tcsh cshw was cshw now
5 == 05 false true false
0 == 00 false true false
10 == 010 false true false
007 == 7 false true false
-5 == -05 false true false
1e2 == 100 false true false

It reads as a convenience — if ($day == "07") matching day 7 — right up to
the moment the same rule makes if ($ver == "1.0") and if ($ver == "1.00")
disagree about the same version, or decides two zero-padded ids are the same
id.

It is not theoretical. Turning it on found five assertions in cshw's own test
suite that were passing *because* of it: two expected 100^20 with one zero
too many, and both sides overflowed a 64-bit parse to the same value, so a
numeric == called a wrong answer right. Three more compared a byte count
against "0" and passed on an empty string, because empty counted as
numeric zero — a missing file read as a passing test.

If you want the numeric reading, say so. Three cast keywords, on either
operand, set the comparison for the whole expression:

if ( num $month == "01" ) # 1 == 1 true
if ( @ $month == "01" ) # same, spelled the way @ already means
if ( str $month == "01" ) # "1" vs "01" false -- the default, said aloud

@ is spelled that way because it is already cshw's arithmetic tier; the cast
is that same idea pulled into a condition. It compares as a float when either
side has a fraction or an exponent, so @ 5 == 5.0 is true and
@ 0.5 == 0.4 is not.
…

Full release notes »