31–40 of 110 posts
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When you evaluate a form deep in a function, how do you handle variables that are defined "outside"? How can you evaluate such expressions?
Cider (the clojure plugin for emacs) has a variant that prompts you for the the values for those variables.
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Homoiconicity isn't required for that, all you need is to be able to map between source and AST enough to identify expression boundaries. Plenty of development environments for non-homoiconic languages provide the ability to evaluate a selected expression (not just the last one) in a linked REPL on demand. I love the Lisp family, but I don't know why its advocates often sound like they haven't seen a dev environment…
Indeed; I do this every day with Vim and its term command, with Julia, Python, bash, Elixir—it works with any language with a REPL of any kind.
In Clojure, you literally built your program in memory while you’re writing the source code file, updating the memory representation of your running program part-by-part without ever stopping it.
This experience is absolutely magical, and it’s very hard to go back to edit-compile-run loop in other languages after that. It is completely different from “my language has a REPL and I can execute parts of code in it”.
I think you might be missing the main "aha!" of clojure REPLs vs REPLs in non-homoiconic languages: you can very easily execute small parts of the program you're editing without re-typing the code. In emacs, for instance, you often use `eval-last-sexp`, by default bound to C-x C-e. This lets you move your cursor to a particular point in the file, often deep in a function, and get the results of just the form(s) you'r…
When you evaluate a form deep in a function, how do you handle variables that are defined "outside"? How can you evaluate such expressions?
Use "man bash" to find the list of built-in commands. Scroll way down, or search for "SHELL BUILTIN COMMANDS".
The "e" command-line switch to the set command tells the script to exit immediately if there is a non-zero return value. The "u" switch tells the shell to treat unset variables as errors when performing parameter expansion. The "o" switch enables the following option (in this case "pipefail"). "pipefail" tells the script to return the value of the rightmost command that returned with a non-zero value in a pipeline. This is all paraphrased, the details are in the man page.
I think you might be missing the main "aha!" of clojure REPLs vs REPLs in non-homoiconic languages: you can very easily execute small parts of the program you're editing without re-typing the code. In emacs, for instance, you often use `eval-last-sexp`, by default bound to C-x C-e. This lets you move your cursor to a particular point in the file, often deep in a function, and get the results of just the form(s) you'r…
This is the draw for Jupyter Notebooks as well. Execute code blocks. I remember when I learned this in Matlab. REPL are super nice for this! I've had a hard time in Java, Fortran, etc. in determining the right development patterns that are used in this space to be productive.
Step2, IDE: Right click + Run.
Step2, CLI: $ run
Bonus: The test is now part of your automated test suite, and will be ran many times to ensure things don't break.
> Don’t forget the set -euo pipefail at the beginning of your script. What does -euo means? I don’t know, I copy-pasted it and man set said there is no manual entry for set. Use "man bash" to find the list of built-in commands. Scroll way down, or search for "SHELL BUILTIN COMMANDS". The "e" command-line switch to the set command tells the script to exit immediately if there is a non-zero return value. The "u" switch…
Earlier quoted context omitted.
When you evaluate a form deep in a function, how do you handle variables that are defined "outside"? How can you evaluate such expressions?
Cursive has a repl powered debugger just put your breakpoint there use the repl to trigger the call then use intellji's debugger to step through If you want to run expressions in context just use the expression editor like a normal repl Something I haven't tried yet is redefining functions at debug time can't see why it wouldn't work though
Earlier quoted context omitted.
Homoiconicity isn't required for that, all you need is to be able to map between source and AST enough to identify expression boundaries. Plenty of development environments for non-homoiconic languages provide the ability to evaluate a selected expression (not just the last one) in a linked REPL on demand. I love the Lisp family, but I don't know why its advocates often sound like they haven't seen a dev environment…
Homoiconicity is an ill-defined concept. If you take every subjective feature from it, all it implies is that you are able to cut your code into well defined AST structures (what all languages have, but for some it's easier than for others). So, yeah, anything people do with Lisp could be done for any other language, it only requires more complex tooling. How much more complexity depending on the language, and it var…
Earlier quoted context omitted.
Indeed; I do this every day with Vim and its term command, with Julia, Python, bash, Elixir—it works with any language with a REPL of any kind.
I am not familiar with how Julia and Elixir work, but form my experience Python’s REPL is not the same at all as REPL in Clojure or other lisps. In Clojure, you literally built your program in memory while you’re writing the source code file, updating the memory representation of your running program part-by-part without ever stopping it. This experience is absolutely magical, and it’s very hard to go back to edit-co…