user-stories.org

Must-have

Interactive REPL

User: I want to type in a program / expression and execute it.

Goal: So that I can prototype and experiment with different ideas I have rapidly.

User: I want to evaluate a complete program.

Goal: So that I can evaluate a complete program in the same way as any source file would be interpreted.

User: I want to evaluate an incomplete program (e.g. a single expression).

Goal: So that I don’t have to provide unecessary and verbose details which are already implicit in the current environment I am working in.

Works with any language defined in Spoofax

Optionally recognizes language-specific REPL commands defined in an esv file

User: I want to define a REPL command specific to my language.

Goal: So that I can provide more support that is tailored to my language, without having to extend my language outside of the context of a REPL.

Input history

User: I want to access the history of previously entered expressions (input history)

Goal: So that I can modify expressions without having to rewrite everything.

User: I want to access the input history of a previous REPL session.

Goal: So that I can keep the history when I quit and resume my session later.

Automatic binding of previously yielded values

User: I want to be able to reference the result of a previous evaluation.

Goal: So that I can easily reuse them in future expressions, and don’t have to assign them myself if I forgot to do that after entering it.

Multiline input editing

User: I want to be able to enter multiline constructs.

Goal: So that I can enter more complex language constructs than just expressions that fit on a single line.

User: I want to be able to see in which mode I am typing (single-/multiline).

Goal: So that I can distinguish between the different mode. So that I can have feedback from the interface of what I am doing.

User: I want to have access to keyboard shortcuts.

Goal: So that I can edit the input efficiently.

Error reporting

User: I want to see errors of the input I have entered before.

Goal: So that I can correct my program.

Syntax checked expressions

User: I want to see errors in the input as I type it.

Goal: So that I can correct my input and the feedback is more rapid, to support rapid prototyping.

Syntax highlighting

User: I want to see syntax highlighting in the input as I type it.

Goal: So that I can distinguish between different syntactical elements.

Integration with Eclipse

User: I want to have back-and-forth interaction with the Eclipse while using the REPL

Goal: So that I can quickly see additional code information, such as the type or value of a variable.

User: I want to use the REPL as plugin in Eclipse

Goal: So that I don’t have to switch from the IDE to the REPL, but can use it in the same session.

Should-have

Ability to redefine identifiers

User: I want to be able to redefine terms that are bound to identifiers.

Goal: So that I can change definitions inside my REPL when I change my mind.

Environment inspection

User: I want to list the current environment.

Goal: So that I can the context in which I am typing the current input.

User: I want to show the type of variables in the environment.

Goal: So that I can have more information what kind of values are in the environment.

Save and load REPL state

User: I want to have a persistent session.

Goal: So that I can resume my work without having to reevaluate everything.

Could-have

(Syntactic) Code completion (Spoofax does not yet offer semantic completion)

User: I want to have code completed when I press TAB.

Goal: So that I don’t have to type everything myself, and don’t have to remember exactly how to type it

Hover over variables to see value, type and others

User: I want to see the value and type of a term when hovering over it.

Goal: So that I can use the REPL in the same way as I use the editor in the IDE as I expect it to, and without listing the entire environment.

Literate programming

User: I want to combine my code with documentation and the results of their execution.

Goal: So that I can make note documents which I can share with others and save for later.

Integration with other IDEs (IntelliJ)

User: I want to be able to use the REPL in a IDE other than Eclipse

Goal: So that I am not tied to using Eclipse because the REPL is not available somewhere else.

Won’t-have

GDB-style debugging and nested REPLs