# Experimenting with skills for Copilot For Excel

> Source: <https://gist.github.com/CHatmaker/c443849f6584a2014e50e6bdabc82e02>
> Published: 2026-05-28 21:59:44+00:00

| # 5G LAMBDA Template Skill | |
| # Version: 1.4 | |
| # Last Updated: May-20-2026 | |
| skill: | |
| name: lambda-template-5g | |
| description: > | |
| Rules and conventions for creating well-structured Excel LAMBDA functions | |
| with inline help documentation using the Advanced Formula Environment (AFE). | |
| Follows 5th Generation Modeling standards from 5gmodelling.com. | |
| category: Excel | |
| tags: | |
| - LAMBDA | |
| - AFE | |
| - Excel Labs | |
| - Named Functions | |
| - Documentation | |
| - 5G Modeling | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| # TRIGGER PHRASES | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| triggers: | |
| - "Make 5g" | |
| - "Make LAMBDA" | |
| - "Convert to 5g" | |
| - "Convert to LAMBDA" | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| # WORKFLOW | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| workflow: | |
| description: > | |
| Step-by-step process to convert a formula into a 5G LAMBDA function. | |
| Do not scan the workbook before taking step 1. | |
| steps: | |
| - step: 1 | |
| action: Ask for user's name | |
| prompt: "What name shall I use for version control?" | |
| usage: Used in REVISIONS section and VERSION line | |
| - step: 2 | |
| action: Ask for formula | |
| prompt: "Select formulas to convert into a 5G LAMBDA function." | |
| usage: Identifies parameters and core logic | |
| - step: 3 | |
| action: Display parameters and ask if any are optional | |
| prompt: "Are any of these inputs optional? If yes, which ones and what is each optional parameter's default value?" | |
| usage: Determines bracket conventions and default value logic | |
| - step: 4 | |
| action: Display suggested function names and ask for function name | |
| prompt: "What would you like to name this function? (e.g., MonthlyPaymentλ)" | |
| usage: Used throughout the LAMBDA definition and help text | |
| - step: 5 | |
| action: Add to names collection | |
| description: Add the 5G LAMBDA function to the workbook's names collection | |
| - step: 6 | |
| action: Test the function | |
| description: Find an empty space below the original example and run the 5g function with the same inputs as the original example. | |
| Leave the test results for the user to examine. Do not clean them up. | |
| - step: 7 | |
| action: Compare results | |
| description: Compare the 5G function's output to the original example to verify correctness | |
| - step: 8 | |
| action: Display Source | |
| description: Write the fully commented source to the chat window. Use TEMPLATE STRUCTURE as a guide. | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| # RULES | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| rules: | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 1. PLACEHOLDER BRACKETS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| placeholder_brackets: | |
| description: > | |
| Template placeholders like <description> are instructional only. | |
| Remove the angle brackets (<>) in the generated output. | |
| example: | |
| template: "<Calculates the monthly payment>" | |
| output: "Calculates the monthly payment" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 2. USER NAME | |
| # ───────────────────────────────────────────────────────────────────────── | |
| user_name: | |
| description: > | |
| Always ask for the user's name at the start of the workflow. | |
| Use it in the REVISIONS section and VERSION line. | |
| prompt: "What is your name?" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 3. DATE HANDLING | |
| # ───────────────────────────────────────────────────────────────────────── | |
| date_handling: | |
| description: > | |
| Use the current date for the REVISIONS section and VERSION line. | |
| format: "Mmm-dd-yyyy" | |
| example: "May-15-2026" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 4. OPTIONAL PARAMETERS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| optional_parameters: | |
| description: > | |
| Ask if any inputs are optional. If yes, ask which ones and | |
| what each optional parameter's default value is. | |
| prompt: "Are any of these inputs optional? If yes, which ones and what is each optional parameter's default value?" | |
| handling: | |
| lambda_definition: "All arguments use [brackets]" | |
| help_text_function_line: | |
| required: "NO brackets (e.g., Amount)" | |
| optional: "WITH brackets (e.g., [Term])" | |
| help_text_parameters: | |
| required: "(Required) description" | |
| optional: "(Optional) Default: value. description" | |
| let_section: > | |
| Add default value assignment for optional params: | |
| ParamName, IF(ISOMITTED(ParamName), DefaultValue, ParamName), | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 5. ARGUMENT BRACKETS CONVENTION | |
| # ───────────────────────────────────────────────────────────────────────── | |
| argument_brackets: | |
| description: > | |
| All arguments must appear optional to Excel so help text can display | |
| when required arguments are omitted. The help text signals which are | |
| truly required by omitting brackets. | |
| lambda_definition: | |
| required: "[Argument]" | |
| optional: "[Argument]" | |
| help_text_function_line: | |
| required: "ARGUMENT" | |
| optional: "[Argument]" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 6. TEXTSPLIT DELIMITERS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| textsplit_delimiters: | |
| description: > | |
| TEXTSPLIT creates a formatted help table that displays | |
| in the Excel grid when required arguments are omitted. | |
| syntax: 'TEXTSPLIT( text, "→", "¶" )' | |
| delimiters: | |
| column: "→" | |
| row: "¶" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 7. MULTI-ROW PARAMETER DESCRIPTIONS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| multi_row_descriptions: | |
| description: > | |
| When a parameter description needs multiple rows in the grid display, | |
| use a leading "→" on continuation lines for proper column alignment. | |
| example: | | |
| " PositiveOnly? →(Optional) TRUE: Outflows are entered as positive values ¶" & | |
| "→ that this function will subtract from the opening balance. ¶" & | |
| "→ FALSE: Outflows are entered as negative values. Default is FALSE." | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 8. LET STEP RESULTS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| let_step_results: | |
| description: > | |
| Name the last calculation in the LET Function. | |
| Use that name as the last step in the LET function. | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 9. EXCEL SYNTAX RULES | |
| # ───────────────────────────────────────────────────────────────────────── | |
| excel_syntax: | |
| description: > | |
| Follow standard Excel conventions for function names and booleans. | |
| booleans: "Uppercase: FALSE, TRUE" | |
| function_names: "Uppercase: AVERAGE(), INDEX(), SCAN(), REDUCE(), PMT()" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 10. STRING CONCATENATION | |
| # ───────────────────────────────────────────────────────────────────────── | |
| string_concatenation: | |
| description: > | |
| Ensure all help text lines are properly concatenated with the & operator. | |
| rule: "Every line except the last must end with &" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 11. INDEX BEHAVIOR | |
| # ───────────────────────────────────────────────────────────────────────── | |
| index_behavior: | |
| description: > | |
| When working with single-row arrays, INDEX interprets the second | |
| argument as the column number. | |
| rule: "When array is a single row, INDEX(array, n) returns the nth column value" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 12. MULTIPLE FORMULAS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| multiple_formulas: | |
| description: > | |
| When the user selects multiple cells containing formulas, | |
| include all of them in the LAMBDA function. | |
| handling: | |
| - Identify all formulas in the selected range | |
| - Combine them logically within a single LAMBDA | |
| - Create appropriate parameters for all unique inputs across formulas | |
| - Document each formula's purpose in the help text | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 13. INPUT CELL DETECTION | |
| # ───────────────────────────────────────────────────────────────────────── | |
| input_cell_detection: | |
| description: > | |
| When formulas reference cells outside the selected range, determine | |
| which cells become LAMBDA inputs based on their content. | |
| rules: | |
| - If a referenced cell contains a value (not a formula), it becomes an input | |
| - If a referenced cell contains a formula that only references another cell | |
| (passthrough), follow the reference chain to find the true input | |
| - If a referenced cell contains a formula with calculations, that cell | |
| itself becomes an input | |
| example: | |
| scenario: "Selected formula references B5, and B5 contains =C3" | |
| result: "C3 becomes the input, not B5 (B5 is a passthrough)" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 14. HORIZONTAL SEQUENCE FOR SCAN | |
| # ───────────────────────────────────────────────────────────────────────── | |
| horizontal_sequence_scan: | |
| description: > | |
| When using SCAN to build a horizontal array, use SEQUENCE(1, n) | |
| instead of SEQUENCE(n) to avoid needing TRANSPOSE afterward. | |
| rule: "SEQUENCE(1, Term) produces horizontal output directly from SCAN" | |
| example: | |
| inefficient: | | |
| CloseBal, SCAN(Amount, SEQUENCE(Term), LAMBDA(bal, n, formula)), | |
| CloseRow, TRANSPOSE(CloseBal), | |
| elegant: | | |
| CloseBal, SCAN(Amount, SEQUENCE(1, Term), LAMBDA(bal, n, formula)), | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 15. DROP VS TAKE FOR ARRAY SLICING | |
| # ───────────────────────────────────────────────────────────────────────── | |
| drop_vs_take: | |
| description: > | |
| When removing elements from the end of an array, prefer DROP over TAKE | |
| to avoid referencing array length variables. | |
| rule: "Use DROP(array, , -1) instead of TAKE(array, 1, Length-1)" | |
| example: | |
| inefficient: "OpenBal, HSTACK(Amount, TAKE(CloseBal, 1, Term-1))" | |
| elegant: "OpenBal, HSTACK(Amount, DROP(CloseBal, , -1))" | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 16. FIXED RANGE ARGUMENTS | |
| # ───────────────────────────────────────────────────────────────────────── | |
| fixed_range_arguments: | |
| description: > | |
| Convert arguments that cover multiple columns to arrays | |
| rule: "Determine which argument sets the number of columns (columns) in the result. | |
| Expand multi-cell, fixed range arguments (argument) using EXPAND( argument, 1, columns, 0)." | |
| purpose: "Makes sure argument sizes remain dynamic ad agree with other array sizes." | |
| # ───────────────────────────────────────────────────────────────────────── | |
| # 17. MATCH EXAMPLE OUTPUT | |
| # ───────────────────────────────────────────────────────────────────────── | |
| match_example_output: | |
| description: > | |
| match the function's output to the example's output | |
| rule: "Include in the function's output all selected formula rows. Copy formats from the example to the output." | |
| purpose: "Keep the users desired output." | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| # TEMPLATE STRUCTURE | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| template: | |
| description: > | |
| Standard structure for 5G LAMBDA functions with inline documentation. | |
| code: | | |
| /* FUNCTION NAME: Functionλ | |
| DESCRIPTION:*//**Description of what the function does*/ | |
| /* REVISIONS: Date Developer Description | |
| Mmm dd yyyy UserName Copyright/Initial Release | |
| */ | |
| Functionλ = LAMBDA( | |
| // Function Arguments | |
| [Required1], // Description | |
| [Required2], // Description | |
| [Optional1], // Description (default: value) | |
| // Check required arguments | |
| IF( OR( ISOMITTED(Required1), | |
| ISOMITTED(Required2) | |
| ), | |
| // Display inline help text | |
| TRIM(TEXTSPLIT( | |
| "FUNCTION: →Functionλ( Required1, Required2, [Optional1])¶" & | |
| "DESCRIPTION: →Description of what the function does¶" & | |
| "WEBPAGE: →https://5gmodelling.com¶" & | |
| "VERSION: →UserName, Mmm-dd-yyyy¶" & | |
| "PARAMETERS: →¶" & | |
| " Required1 →(Required) Description¶" & | |
| " Required2 →(Required) Description¶" & | |
| " Optional1 →(Optional) Default: value. Description", | |
| "→", "¶")), | |
| // Main function logic | |
| LET( | |
| // Set Defaults | |
| Optional1, IF(ISOMITTED(Optional1), DefaultValue, Optional1), | |
| // Calculations | |
| Result, formula, | |
| Result | |
| ) | |
| ) | |
| ); | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| # CHECKLIST | |
| # ═══════════════════════════════════════════════════════════════════════════ | |
| checklist: | |
| - "Function name matches throughout (definition, help text FUNCTION line)" | |
| - "All brackets correct in LAMBDA definition [Argument]" | |
| - "Help text FUNCTION line: required args NO brackets, optional args WITH brackets" | |
| - "All & concatenation operators present between help text lines" | |
| - "TEXTSPLIT delimiters correct: \"→\", \"¶\" (column, row)" | |
| - "All parentheses balanced (TEXTSPLIT, TRIM, IF, LET, LAMBDA)" | |
| - "Boolean values uppercase: FALSE, TRUE" | |
| - "Function names uppercase: AVERAGE, INDEX, SCAN, REDUCE" | |
| - "Multi-row descriptions use leading \"→\" for continuation lines" | |
| - "Optional params have default value logic in LET section" | |
| - "User's name appears in REVISIONS and VERSION" | |
| - "Current date used in REVISIONS and VERSION" | |
| - "No angle brackets (<>) in final output" | |
| - "If multiple formulas selected, all are included in the LAMBDA" | |
| - "Follow input cell detection rules for passthrough references" | |
| - "Use SEQUENCE(1, n) for horizontal arrays in SCAN operations" | |
| - "Prefer DROP over TAKE when removing elements from array" |