ControlFlow.mdx

description
This page documents control flow. Squiggle has if/else statements, but not for loops.

import { SquiggleEditor } from "../../../components/SquiggleEditor";

Control Flow

This page documents control flow. Squiggle has if/else statements, but not for loops. But for for loops, you can use reduce/map constructs instead, which are also documented here.

Conditionals

If-else

if condition then result else alternative

<SquiggleEditor defaultCode={x = 10 if x == 1 then 1 else 2} />

If-else as a ternary operator

test ? result : alternative;

<SquiggleEditor defaultCode={x = 10 x == 0 ? 1 : 2} />

Tips and tricks

Use brackets and parenthesis to organize control flow

<SquiggleEditor defaultCode={x = 10 if x == 1 then { 1 } else { 2 }} />

or

<SquiggleEditor defaultCode={x = 10 y = 20 if x == 1 then { ( if y == 0 then { 1 } else { 2 } ) } else { 3 }} />

This is overkill for simple examples becomes useful when the control conditions are more complex.

Save the result to a variable

Assigning a value inside an if/else flow isn't possible:

x = 10
y = 20
if x == 1 then {
  y = 1
} else {
  y = 2 * x
}

Instead, you can do this:

<SquiggleEditor defaultCode={x = 10 y = 20 y = if x == 1 then { 1 } else { 2 * x }} />

Likewise, for assigning more than one value, you can't do this:

y = 0
z = 0
if x == 1 then {
  y = 2
} else {
  z = 4
}

Instead, do:

<SquiggleEditor defaultCode={x = 10 result = if x == 1 then { {y: 2, z: 0} } else { {y: 0, z: 4} } y = result.y z = result.z} />

For loops

For loops aren't supported in Squiggle. Instead, use a map or a reduce function.

Instead of:

xs = [];
for (i = 0; i < 10; i++) {
  xs[i] = f(x);
}

do:

<SquiggleEditor defaultCode={f(x) = 2*x xs = List.upTo(0,10) ys = List.map(xs, {|x| f(x)})} />