4 ms·

The generated code already looks kind of insane, I can imagine it would only be worse without the benefit of Bash features.

sgarland 2y ago
THIS. Why does this: if age < 18 { echo "I'm not an adult yet" } else { echo "I'm an adult" } compile to this: __0_age=30; if [ $(echo ${__0_age} '<' 18 | bc -l | sed '/\./ s/\. \{0,1\} 0\{1,\}$//') != 0 ]; then echo "I'm not an adult yet" else echo "I'm an adult" fi instead of this: __0_age=30; if [[ ${__0_age} -lt 18 ]]; then ... If you're going to compile to Bash, then use Bash-isms. EDIT: `-gt` is POSIX, but tbf if there's no input sanitization, then bash (or sh) will choke on the float. In that case, as long as you aren't trying to round, you could use parameter substitution to truncate: __0_age=17.6; if [[ ${__0_age%%\.*} -lt 18 ]]; then ... EDIT2: TIL that parameter substitution is POSIX [0] Section 2.6.2 [0]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V...
- nick238 2y ago
  So you want it to compile to POSIX sh but you're unhappy it doesn't use more POSIX-incompatible features? Maybe full POSIX sh compat is WIP, or in some simpler cases maybe it already is?
  - olejorgenb 2y ago
    Retr0id, not sgarland want posix. > Maybe full POSIX sh compat is WIP Still - I sure hope it's possible to do a comparison in sh without spawning two processes.
    - sgarland 2y ago
      As I've just updated my comment to reflect, TIL that parameter substitution is supported (with some exceptions) by `sh`. More broadly though, yes, there's a tendency for people to pop sub-shells without giving it a second thought. Those aren't free; use shell built-ins whenever possible!
- jimrandomh 2y ago
  There might be reasons to use `bc` like this if you don't know the type of `age` and it could be a non-numeric string. Buuuuut a programming language where a simple integer-comparison leads to two subprocesses is going to be slower than the slowest existing programming languages, by orders of magnitude.
  - chme 2y ago
    Right. And the check/type validation shouldn't happen on comparison, but on assignment and only if it is dynamically assigned.
  - sgarland 2y ago
    Am I missing something, like `bc` can parse `one + two`? Input sanitizing should be done before trying to hand inputs over to be summed.
    - chme 2y ago
      The amber source of that is [here](https://docs.amber-lang.com/basic_syntax/basic_syntax https://docs.amber-lang.com/basic_syntax/basic_syntax) and contains: // Define variables let name = "John" let age = 30 // Display a greeting echo "Hello, my name is {name}" // Perform conditional checks if age < 18 { echo "I'm not an adult yet" } else { echo "I'm an adult" } So there is no input, everything is known statically. No sanitation required. Any additional checks done by amber in the bash code is unnecessary.
- joveian 2y ago
  "if ((age < 18)) ; then ..." works in bash.
Retr0id 2y ago
The alternative stance is that if it's already bad, can't hurt to make it worse ;) Something you could do to alleviate this is to interleave comments with the original Amber source, along with line numbers (which would balloon the script size, but probably not a huge deal). Edit: you could also bundle a tool to recover the original Amber source from those comments, to allow for easy in-the-field script edits and/or audits.

sgarland 2y ago

THIS. Why does this: if age < 18 { echo "I'm not an adult yet" } else { echo "I'm an adult" } compile to this: __0_age=30; if [ $(echo ${__0_age} '<' 18 | bc -l | sed '/\./ s/\. \{0,1\} 0\{1,\}$//') != 0 ]; then echo "I'm not an adult yet" else echo "I'm an adult" fi instead of this: __0_age=30; if [[ ${__0_age} -lt 18 ]]; then ... If you're going to compile to Bash, then use Bash-isms. EDIT: `-gt` is POSIX, but tbf if there's no input sanitization, then bash (or sh) will choke on the float. In that case, as long as you aren't trying to round, you could use parameter substitution to truncate: __0_age=17.6; if [[ ${__0_age%%\.*} -lt 18 ]]; then ... EDIT2: TIL that parameter substitution is POSIX [0] Section 2.6.2 [0]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V...

nick238 2y ago
So you want it to compile to POSIX sh but you're unhappy it doesn't use more POSIX-incompatible features? Maybe full POSIX sh compat is WIP, or in some simpler cases maybe it already is?
- olejorgenb 2y ago
  Retr0id, not sgarland want posix. > Maybe full POSIX sh compat is WIP Still - I sure hope it's possible to do a comparison in sh without spawning two processes.
  - sgarland 2y ago
    As I've just updated my comment to reflect, TIL that parameter substitution is supported (with some exceptions) by `sh`. More broadly though, yes, there's a tendency for people to pop sub-shells without giving it a second thought. Those aren't free; use shell built-ins whenever possible!
jimrandomh 2y ago
There might be reasons to use `bc` like this if you don't know the type of `age` and it could be a non-numeric string. Buuuuut a programming language where a simple integer-comparison leads to two subprocesses is going to be slower than the slowest existing programming languages, by orders of magnitude.
- chme 2y ago
  Right. And the check/type validation shouldn't happen on comparison, but on assignment and only if it is dynamically assigned.
- sgarland 2y ago
  Am I missing something, like `bc` can parse `one + two`? Input sanitizing should be done before trying to hand inputs over to be summed.
  - chme 2y ago
    The amber source of that is [here](https://docs.amber-lang.com/basic_syntax/basic_syntax https://docs.amber-lang.com/basic_syntax/basic_syntax) and contains: // Define variables let name = "John" let age = 30 // Display a greeting echo "Hello, my name is {name}" // Perform conditional checks if age < 18 { echo "I'm not an adult yet" } else { echo "I'm an adult" } So there is no input, everything is known statically. No sanitation required. Any additional checks done by amber in the bash code is unnecessary.
joveian 2y ago
"if ((age < 18)) ; then ..." works in bash.

Retr0id 2y ago

The alternative stance is that if it's already bad, can't hurt to make it worse ;) Something you could do to alleviate this is to interleave comments with the original Amber source, along with line numbers (which would balloon the script size, but probably not a huge deal). Edit: you could also bundle a tool to recover the original Amber source from those comments, to allow for easy in-the-field script edits and/or audits.