A quick tour of Neo.

Three bracket types

Neo makes the difference between typed data, mixed data, and executable code visible.

[1 2 3 4]                    ; homogeneous data

(name:"Neo" version:3)       ; dictionary data

{+ 1 2}                       ; executable call

The same function works on scalars and vectors

Define the operation once. A scalar call returns a scalar. A vector call lifts the same function across the data.

{def square (x)
  {* x x}}

{square 5}
{square [1 2 3 4]}

{+ [1 2 3] 10}

Unknown and error are ordinary values

? represents unknown or missing data. ! represents a runtime error value. Both can appear inside normal vectors.

{var readings [21.4 ? 22.8 23.1]}

{missing? ?}
{missing? 42}
{mean readings}

Statistics such as mean, variance, sd, min, and max operate on known entries.

Three-way control flow

A Neo condition may be true, false, or unknown. A vector condition selects a branch for each element.

{if [T F ?]
  [10 20 30]
  [1 2 3]
  [100 200 300]}

Element-wise or Cartesian

Normal vector operations are element-wise. The @ spread operator requests every combination.

{+ [1 2 3] [10 20 30]}
; [11 22 33]

{+ @[1 2] @[10 20 30]}
; [[11 21 31] [12 22 32]]

Strings use vector-style operations

Concatenation, push, and pop work on strings. Compiled programs can read user arguments with args.

{& "Neo" " language"}
{push "Ne" "o"}
{pop "Neo"}

{print {args}}

neo show-args.neo -o show-args.exe
.\show-args.exe alpha beta

Code can remain data

Store executable vectors inside (), transform the data, and cross into execution explicitly with {run}.

{var pipeline
  ({print "read"}
   {print "transform"}
   {print "write"})}

{run pipeline}

{set pipeline
  {& pipeline ({print "complete"})}}

Numerical computing is built in

{var z (3 4i)}
{abs z}

{* 2 1i}
{/ 2i 2}

{def layer (input weights bias)
  {relu {+ {matmul input weights} bias}}}

Compile a Neo program

The Windows installer includes Neo, its runtime headers, and examples.

neo --version
neo --doctor
neo hello.neo -o hello.exe
.\hello.exe

Build and run the interpreter written in Neo

The interpreter source lives at Neo-interpreter-written-in-Neo/src/interpreter.neo. Compile it with the native Neo compiler, then open the REPL.

neo .\Neo-interpreter-written-in-Neo\src\interpreter.neo -o .\Neo-interpreter-written-in-Neo\interpreter.exe

.\Neo-interpreter-written-in-Neo\interpreter.exe

Run a file first and the REPL continues with the same persistent environment:

.\Neo-interpreter-written-in-Neo\interpreter.exe .\program.neo