nw-fp-fsharp

nw-fp-fsharp is a skill for Claude Code from nWave-ai/nWave. It costs 21 tokens per session (1,802 once invoked), scanned A, original, MIT.

A guide to functional programming in F#, including domain modeling, pipeline-based code, and structured error handling on .NET.

In plain words
What is it for?
Use it to build F# applications, model domain choices, connect related operations into pipelines, and run automated tests.
Why use it?
It helps .NET teams express business rules and failure paths clearly without relying on large object-oriented designs.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter. Also seen: agent in frontmatter.

Good fit Use it to build F# applications, model domain choices, connect related operations into pipelines, and run automated tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nwave-ai/nwave/nw-fp-fsharp
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add nWave-ai/nWave --skill nw-fp-fsharp
Clone the repo
git clone --depth 1 https://github.com/nWave-ai/nWave

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for nw-fp-fsharp

README.md
[![agentmods](https://agentmods.dev/badge/skills/nwave-ai/nwave/nw-fp-fsharp.svg)](https://agentmods.dev/skills/nwave-ai/nwave/nw-fp-fsharp)
Your own site
<a href="https://agentmods.dev/skills/nwave-ai/nwave/nw-fp-fsharp"><img src="https://agentmods.dev/badge/skills/nwave-ai/nwave/nw-fp-fsharp.svg" alt="Measured on agentmods" height="20"></a>
Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,802 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00021 $0.01802
Opus 5 $0.00010 $0.00901
Sonnet 5 $0.00004 $0.00360
Haiku 4.5 $0.00002 $0.00180

Measured 5d ago against content hash 56bf18d4ab67, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

nw-fp-fsharp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

nWave/skills/nw-fp-fsharp/SKILL.md · 219 lines

How it starts

The opening of the file, as written. The whole thing — 219 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FP in F# -- Functional Software Crafter Skill

Cross-references: fp-principles | fp-domain-modeling | property-based-testing

When to Choose F#

  • Best for: domain modeling on .NET | DDD | railway-oriented programming | pipeline-first design | finance
  • Not ideal for: teams needing higher-kinded types | non-.NET platforms | large existing C# codebases resistant to change

[STARTER] Quick Setup

dotnet new console -lang F# -o OrderService && cd OrderService
dotnet new xunit -lang F# -o OrderService.Tests
dotnet add OrderService.Tests reference OrderService
dotnet add OrderService.Tests package FsCheck.Xunit
dotnet test

File order matters: F# compiles files top-to-bottom as listed in .fsproj. Types must be defined before use.

[STARTER] Type System for Domain Modeling

Choice Types (Discriminated Unions)

type PaymentMethod =
    | CreditCard of cardNumber: string * expiryDate: string
    | BankTransfer of accountNumber: string
    | Cash

Record Types and Domain Wrappers

type Customer = {
    CustomerId: CustomerId
    CustomerName: CustomerName
    CustomerEmail: EmailAddress
}

type OrderId = OrderId of int
type EmailAddress = EmailAddress of string

Records have structural equality by default. Single-case DUs have small runtime cost (unlike Haskell's zero-cost newtype).

[STARTER] Validated Construction (Smart Constructors)

module EmailAddress =
    let create (rawEmail: string) : Result<EmailAddress, string> =
        if rawEmail.Contains("@") then Ok (EmailAddress rawEmail)
        else Error $"Invalid email: {rawEmail}"

    let value (EmailAddress email) = email

[INTERMEDIATE] Composition Style

Pipeline Operator (The Defining Feature)

let processOrder rawOrder =
    rawOrder
    |> validateOrder
    |> Result.bind priceOrder
    |> Result.bind confirmOrder
    |> Result.map generateReceipt

Read the full file on GitHub · 219 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 219 lines · 21 tokens per session scan A 56bf18d4ab67

Subscribe to this mod's changes

nw-fp-fsharp is a skill published in the GitHub repository nWave-ai/nWave (608 stars, last pushed 2d ago), licensed MIT. It adds 21 tokens to every session and 1,802 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.