F# — 144 Operations for AI Agents

This page is the canonical reference an AI coding agent uses to refactor, query, and analyze F# code through the act MCP server. 144 operations available: 70 refactor, 18 query, 42 analysis, 14 verification. Each operation is callable from Claude Code, Cursor, Codex, OpenCode, or any MCP-compatible agent host. Click any operation for a stable anchor link suitable for citation.

Worked F# examples

act101 rewrites F# expressions at the syntax-tree level: it can add a when guard to a pattern-match case, insert an open declaration for a module, collapse two consecutive List.map stages of a pipeline into one, and collapse nested function calls into a |> pipeline. Each operation locates its target — a match arm, an if expression, an insertion point, a call chain — by walking the parsed source, so the same edit applies regardless of how the surrounding code is formatted. Because F# favors expressions over statements, act101's conversions rewrite one expression form into an equivalent one rather than inserting imperative scaffolding. Each example below is the verbatim output of the command shown, run against the file shown.

Add a guard to a pattern-match case

option.fs matches x with Some n -> n and None -> 0, with no condition on n.

$ act refactor-lang add_guards_to_pattern --file option.fs --params '{"guard_condition":"x > 0","line":2,"column":3}'

Before

match x with
| Some n -> n
| None -> 0

After

match x with
| Some n when x > 0 -> n
| None -> 0

The Some n -> n arm becomes Some n when x > 0 -> n, so that arm only matches when the guard holds.

Add an open declaration for a module

classify.fs uses List functions but opens no modules.

$ act refactor-lang add_module_open --file classify.fs --params '{"module_name":"System.IO","line":1,"column":1}'

Before

let x = List.map (fun n -> n * 2) [1..10]

After

open System.IO
let x = List.map (fun n -> n * 2) [1..10]

open System.IO is inserted as the first line; the existing binding is left as written.

Collapse two pipeline stages into one

shapes.fs pipes a list through two consecutive List.map calls.

$ act refactor-lang simplify_pipeline --file shapes.fs --params '{"line":1,"column":12}'

Before

let data = list |> List.map (fun x -> x + 1) |> List.map (fun x -> x * 2)

After

let data = list |> List.map (fun x -> (x + 1) * 2)

The two maps fuse into a single List.map whose lambda applies both transformations, (x + 1) * 2, so the list is traversed once.

Convert nested calls to a pipeline

trim.fs computes result by nesting String.length (String.trim input), reading right-to-left.

$ act refactor-lang convert_to_pipeline --file trim.fs --params '{"line":1,"column":14}'

Before

let result = String.length (String.trim input)

After

let result = input |> String.trim |> String.length

The nested calls become input |> String.trim |> String.length, the same two calls applied left-to-right through |>.

Query

18 query tools, the same on every supported language. Descriptions live in the shared reference: /docs/query-tools.

callers control_flow data_flow definition diagnostics effect_closure effect_summary fix_auto get_type graph import_organize interface mutations references repo_outline skeleton symbols symbols_batch

Refactor

Analysis

42 analysis tools, the same on every supported language. Descriptions live in the shared reference: /docs/analysis-tools.

analyze_api_diff analyze_chokepoints analyze_clones analyze_clusters analyze_cohesion analyze_conformance analyze_coupling analyze_cycle_risk analyze_cycles analyze_dead_code analyze_depth analyze_entry_points analyze_export analyze_extraction analyze_fan_balance analyze_features analyze_hotspots analyze_impact analyze_inconsistencies analyze_inheritance analyze_interface_bloat analyze_interfaces analyze_layers analyze_orphan_types analyze_patterns analyze_platform_deps analyze_readiness analyze_roles analyze_seams analyze_stability analyze_surface analyze_test_gaps analyze_thickness analyze_type_completeness churn_hotspots co_change_clusters coverage_overlay ownership_map profile_overlay simulate split_module trace_overlay

Verify

14 verify tools, the same on every supported language. Descriptions live in the shared reference: /docs/verification.

bisect_regression gate generate_test_harness scan secret_surface summarize_pr taint_flow unsafe_surface verify_behavioral_equivalence verify_contract_preserved verify_diff_semantics verify_port_parity verify_side_effects verify_test_impact