1. Code Blocks

Folio supports three code display environments. All render with syntax highlighting.

1.1. lstlisting Environment

Specify the language with [language=...]:

def fibonacci(n: int) -> int:
    """Return the nth Fibonacci number"""
    if n <= 1:
        return n
    a, b = 0, 1
    for _ in range(2, n + 1):
        a, b = b, a + b
    return b

# Usage
for i in range(10):
    print(f"F({i}) = {fibonacci(i)}")

Another language:

interface Article {
  id: string;
  title: string;
  content: string;
  tags: string[];
  createdAt: Date;
}

async function fetchArticle(id: string): Promise<Article> {
  const response = await fetch('/api/articles/' + id);
  if (!response.ok) {
    throw new Error('Article not found: ' + id);
  }
  return response.json();
}

1.2. minted Environment

minted specifies the language in curly braces:

public class BinarySearch {
    public static int search(int[] arr, int target) {
        int left = 0, right = arr.length - 1;
        while (left <= right) {
            int mid = left + (right - left) / 2;
            if (arr[mid] == target) return mid;
            else if (arr[mid] < target) left = mid + 1;
            else right = mid - 1;
        }
        return -1;
    }
}

1.3. Supported Languages

Languages with syntax highlighting support:

1.4. verbatim Environment

Use verbatim to display content as-is without highlighting:

This is displayed as-is.
  Indentation is preserved.
    Special characters $ % & # are not converted.

2. Algorithm Pseudocode

2.1. algorithm + algorithmic Environments

algorithm is a captioned container; algorithmic is the pseudocode body:

\begin{algorithm}
\caption{Euclidean Algorithm}
\begin{algorithmic}
\Function{GCD}{$a, b$}
  \While{$b \neq 0$}
    \State $t \gets b$
    \State $b \gets a \mod b$
    \State $a \gets t$
  \EndWhile
  \Return $a$
\EndFunction
\end{algorithmic}
\end{algorithm}

Result:

2.2. Control Structures

Control structures available in algorithmic:

Conditionals:

\begin{algorithmic}
\If{$x > 0$}
  \State $\text{sign} \gets +1$
\ElsIf{$x < 0$}
  \State $\text{sign} \gets -1$
\Else
  \State $\text{sign} \gets 0$
\EndIf
\end{algorithmic}

Result:

Loops:

\begin{algorithmic}
\For{$i \gets 1$ \KwTo $n$}
  \State $S \gets S + a_i$
\EndFor
\end{algorithmic}

Result:

\begin{algorithmic}
\While{queue is not empty}
  \State $v \gets$ \Call{Dequeue}{}
  \For{$u \in \text{Adj}(v)$}
    \If{$u$ is unvisited}
      \State Mark $u$ as visited
      \State \Call{Enqueue}{$u$}
    \EndIf
  \EndFor
\EndWhile
\end{algorithmic}

Result:

2.3. Input/Output and Preconditions

\begin{algorithmic}
\Require $n \geq 0$ (non-negative integer)
\Ensure Returns $n!$
\Function{Factorial}{$n$}
  \If{$n = 0$}
    \Return $1$
  \EndIf
  \Return $n \times$ \Call{Factorial}{$n - 1$}
\EndFunction
\end{algorithmic}

Result:

2.4. A More Complex Example: Merge Sort

\begin{algorithm}
\caption{Merge Sort}
\begin{algorithmic}
\Function{MergeSort}{$A, l, r$}
  \If{$l < r$}
    \State $m \gets \lfloor (l + r) / 2 \rfloor$
    \State \Call{MergeSort}{$A, l, m$}
    \State \Call{MergeSort}{$A, m+1, r$}
    \State \Call{Merge}{$A, l, m, r$}
  \EndIf
\EndFunction
\end{algorithmic}
\end{algorithm}

Result:

3. Summary

On Folio, both code display (lstlisting, minted) and pseudocode (algorithmic) work with no additional setup. Next, we'll look at diagrams and tables.