Stutter is a minimal language inspired by Lisp.
By minimal we mean that the Stutter interpreter contains the a minimal amount of functions to create a functional language: the "standard library" is written in Stutter itself.
Stutter is inspired by Lisp: it has two main datatypes: S-expressions and F-expressions.
Stutter has a REPL where you can type in expressions and see the result:
stutter> (+ 5 3)
8.0
stutter> + 2 3
5.0
Stutter has a couple of built-in functions (for example show)
stutter> show 20
20.0
()
Functions are called by putting the function first, followed by the arguments. This is the same for math operators:
stutter> + 2 3
5
The show function prints the first argument to stdout, and returns () (an empty S-expression, also called nil)
If one wants to postpone the evaluation of an expression to a later point, one uses [ expr ] to create a fixed expression
stutter> [+ 5 3]
[+ 5 3]
A fixed expression can be evaluated with eval
stutter> eval [+ 5 3]
8
Note that this feature is totally useless in isolation - but with some more language features, it is indispensable.
Stutter has an environment which maps variables onto expressions - def inserts such an expression into the environment.
In order to capture the variable name, the first argument of def needs an f-expression with one or more variable names:
stutter> def [a] 42
()
stutter> a
42.0
stutter> def [b c] 2 3
()
stutter> * b c
6
To create a function:
stutter> fun [plus a b] [+ a b]
()
stutter> plus 40 2
42
The def function defines an F-expression of variables (first argument) to its remaining arguments.
- Install stack
sudo apt install haskell-stack - Clone the repository
- Install the dependencies, run
stack install - Start the interactive haskell shell:
stack repl - In the shell, start the the Stutter-Repl:
main