REPL

A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple, interactive computer programming environment that takes single user inputs (i.e., single expressions), evaluates (executes) them, and returns the result to the user; a program written in a REPL environment is executed piecewise. The term is usually used to refer to programming interfaces similar to the classic Lisp machine interactive environment. Common examples include command line shells and similar environments for programming languages, and the technique is very characteristic of scripting languages.[1]... The most common use for REPLs outside of operating system shells is for instantaneous prototyping. Other uses include mathematical calculation, creating documents that integrate scientific analysis (e.g. IPython), interactive software maintenance, benchmarking, and algorithm exploration. A REPL can become an essential part of learning a new language as it gives quick feedback to the novice. https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop

Online-REPs-and-REPLs list

• includes many Python options
  • but doesn't inclue ptpython
• incl repl.it https://repl.it/