SIGPlan Programming Language

A programming language designed and implemented by SIGPlan over the course of Spring 2026.

---

Table of Contents

• Types
• Variables
• Control Flow
• Functions
• Examples

---

Primitives

Type	Description
int1	Signed 1-byte integer
int2	Signed 2-byte integer
int4	Signed 4-byte integer
int8	Signed 8-byte integer
intu1	Unsigned 1-byte integer
intu2	Unsigned 2-byte integer
intu4	Unsigned 4-byte integer
intu8	Unsigned 8-byte integer

---

Variables

Variables are declared with let. Use change to mutate them.

let x be 42
change x to 100

---

Control Flow

Conditionals

if i is n begin
    ...
end

Loops

loop begin
    ...
    break
end

---

Functions

Declaration

Functions are declared with funct, specify typed parameters, and optionally return a type.

funct foo takes bar is int4, baz is intu1 returns int4 begin
    ...
end

Named Calls

call foo with bar as 8, baz as 10

Anonymous Functions

let foo be funct that takes bar is int4 returns intu4
    ...
end

---

Product Types

Creating an Instance

Use arise to construct a product type, supplying values for each field.

product A contains bar is intu1, baz is int4

let a be arise A with bar as 0, baz as -1

Accessing Fields

let f be member bar of a

---

Sum Types

Creating an Instance

Use arise to construct a sum type variant, supplying values for each field.

sum Shape is Circle contains radius is int4,
             Rect contains width is int4, height is int4,
             Point

let s be arise Circle with radius as 5

Pattern Matching

match s begin
    Circle contains radius begin
        ...
    end
    Rect contains width, height begin
        ...
    end
    Point begin
        ...
    end
end

---

Examples

Fibonacci

Computes the nth Fibonacci number iteratively.

let n be 0
let a be 0
let b be 1
let i be 0

loop begin
    if i is n begin
        break
    end
    let t be b
    change b to a + b
    change a to t
    call print with s as b
end