{ "category": "Information functions", "display_name": "ISOMITTED", "entry_kind": "built_in_function", "eval_api": { "method": "POST", "url": "https://handbook.dnacalc.com/api/eval" }, "function_id": "FUNC.ISOMITTED", "implementation_state": { "answer_bank": null, "detail": "Recorded: 5 workbook cells.", "dnacalc_commit": "9e1884369a678158dd82d3d74188daf986995e87", "in_catalogue": true, "state": "matches", "state_label": "Matches every recorded Excel answer", "summary": "Matches all 5 recorded answers", "workbook_corpus": { "cells": 5, "matched": 5 } }, "implementations": [ { "commit": "9e1884369a678158dd82d3d74188daf986995e87", "flavour": "excel-compatibility-candidate", "language": "Rust", "name": "CalcFunc", "own_code": [ "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/offset.rs#L53-L61", "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/offset.rs#L286-L294" ], "repository": "https://github.com/DnaCalc/DnaCalc", "shared_code": [], "source": "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/offset.rs#L53-L61", "state": "matches", "suite": null, "summary": "Matches all 5 recorded answers" } ], "json_url": "https://handbook.dnacalc.com/api/functions/FUNC.ISOMITTED.json", "name": "ISOMITTED", "notes": [], "schema": "efh.function-reference/v1", "section_order": [ "what-it-does", "try-it", "quirks", "how-to-implement", "version-differences", "alternatives" ], "sections": { "alternatives": "\n### Relationships\n\n\n- **`LAMBDA`** is the function `ISOMITTED` exists to serve; outside it, the function has no\n subject.\n- **`ISBLANK`** is the near neighbour and the standard confusion. `ISBLANK` tests `Empty` — a\n cell with no content. `ISOMITTED` tests `Missing` — a call-site slot with nothing in it. Two\n kinds, two functions, and the model deliberately refuses to conflate them\n ([the value universe](../model/01-value-universe.md), \"Missing versus Empty\").\n- **`MAP`, `REDUCE`, `SCAN`, `BYROW`, `BYCOL`, `MAKEARRAY`** share `ISOMITTED`'s implementation\n module and its callable-helper classification. They consume `LAMBDA` values; `ISOMITTED`\n inspects a `LAMBDA`'s own binding.\n- **`IF`** is the invariable companion: `IF(ISOMITTED(y), , y)` is the idiom, and it is\n worth noting that `IF` is a lazy branch selector\n ([the call pipeline](../model/03-call-pipeline.md)), so the default expression is not evaluated\n when the parameter was supplied.\n- **`LET`** often appears alongside, to name the defaulted value once:\n `LET(yy, IF(ISOMITTED(y), 10, y), …)`.\n- **Optional arguments in built-in functions** are the analogue this function brings to\n user-defined ones: every built-in with an `[optional]` slot performs internally the test that\n `ISOMITTED` exposes.\n\n\n", "how-to-implement": "\n### Notes for implementers\n\n\n1. **`Missing` must survive argument binding.** If a `LAMBDA` invocation normalizes empty slots\n to `Empty` or to `0` before binding parameters, `ISOMITTED` can never return `TRUE`, and the\n failure is silent — every call just takes the non-default branch.\n2. **`ISOMITTED` must not have its argument evaluated to a value first.** It needs the binding,\n not the binding's value. This is a lazier argument treatment than any ordinary function's.\n3. **`Missing` is admitted at exactly one boundary.** It must never be storable in a cell,\n returnable from a function, or publishable as a result. An engine that lets `Missing` leak is\n creating a value Excel cannot represent.\n4. **Decide the nesting behaviour deliberately.** Whether a forwarded parameter carries its\n `Missing` marker into an inner `LAMBDA` determines whether optional parameters compose, and it\n is not documented either way.\n5. **The battery cannot reach the `TRUE` case.** Mechanical probing with ordinary values only\n ever exercises `FALSE`. Any test corpus for this function must be constructed by hand, inside\n `LAMBDA` invocations.\n\n\n", "quirks": "\n### Result and edge cases\n\n\nReturns a `Logical`.\n\n- **`Missing` is not `Empty`.** This is the distinction the whole function rests on. A parameter\n bound to a reference to a *blank cell* received something — the `Empty` kind — and is not\n omitted. `ISOMITTED` should be `FALSE` there and `ISBLANK` `TRUE`. The two functions cover the\n two different nothings, and the model keeps them separate precisely so that they can.\n- **A parameter bound to `0` or `\"\"` is not omitted.** The whole point.\n- **Errors do not propagate.** `ISOMITTED(#N/A)` classifies rather than forwards, in the same way\n the IS-family predicates do — an error argument was supplied, so the answer is `FALSE`.\n- **Trailing omission versus interior omission.** `(1,)` leaves a slot empty at the end;\n `(,2)` leaves one at the start. Both are omissions in the formula-text sense. Whether both\n deliver `Missing` is not established here.\n- **Nested `LAMBDA`s.** A parameter forwarded from one `LAMBDA` to another — does the `Missing`\n marker survive the hop, so that the inner `ISOMITTED` sees it? Not established here, and this\n is the question that determines whether optional parameters compose.\n\n\n\n### Errors\n\n\n`ISOMITTED` returns no error of its own for any argument it can be given.\n\nMicrosoft's page documents no error return.\n\n\n", "sources": "- Microsoft, \"ISOMITTED function\" —\n .\n Read for this page: the description, the syntax, the argument description, the worked `LAMBDA`\n example verbatim, and the stated availability (Excel for Microsoft 365, Excel 2024, and the\n Mac equivalents).\n- Handbook, [coercion and lifting](../model/02-coercion-and-lifting.md) — omitted optional\n arguments delivering the `Missing` marker, and `SUM(1,,2)` as the documented example.\n\n\n", "version-differences": "No comparison between specific Excel builds is recorded here yet. This does not establish that all builds behave alike.", "what-it-does": "\n`ISOMITTED(argument)` returns `TRUE` if the argument slot it was handed was left empty at the\ncall site, and `FALSE` otherwise.\n\nMicrosoft's description: \"Checks whether the value in a LAMBDA is missing and returns TRUE or\nFALSE.\" The argument is \"The value you want to test, such as a LAMBDA parameter.\"\n\nThis is the only worksheet function whose subject is the value kind **`Missing`** — the marker\nthat, in Excel's value universe, exists at exactly one boundary and nowhere else. From\n[the value universe](../model/01-value-universe.md): `Missing` is \"the marker for an argument\nthat was omitted at a call site\"; it is never stored in a cell, never returned by a function,\nnever published by a formula. It is admitted at the call-argument boundary only.\n\n`ISOMITTED` is how that marker becomes visible. Without it, `Missing` is a kind that exists in\nthe engine and can never be observed from the sheet.\n\nThe mechanism `LAMBDA` supplies is the second half of the story. `LAMBDA` lets a user define a\nfunction with parameters; a caller may leave a parameter slot empty (`(1,)`); the empty slot\ndelivers `Missing` to the body; `ISOMITTED` reads it. Microsoft's own example:\n\n```\n=LAMBDA(x,y, IF(ISOMITTED(y),\"Missing second argument\",x+y))(1,)\n```\n\nThat is the whole design pattern — **optional parameters with defaults in user-defined\nfunctions**, which is what `ISOMITTED` exists to make possible. Before it, a `LAMBDA` could not\ndistinguish \"you gave me nothing\" from \"you gave me zero\".\n\n\n### Arguments\n\n\n`argument` — required, exactly one. The published signature is `ISOMITTED(value)`.\n\n- **The intended use is a bare `LAMBDA` parameter name.** `ISOMITTED(y)` inside the body of a\n `LAMBDA(x,y,…)`.\n- **An expression is not a slot.** `ISOMITTED(y+0)` cannot be `TRUE` — the addition produced a\n value, and a value is not missing. Wrapping the parameter in anything destroys the thing being\n tested.\n- **Outside a `LAMBDA` there is nothing to be missing.** `=ISOMITTED(A1)` on a worksheet is\n asking about a cell reference, which was supplied. The documented subject of this function is a\n `LAMBDA` parameter; using it anywhere else is not what it is for, and the Handbook has not\n established what it does there.\n\n\n" }, "signature": { "display": "ISOMITTED(argument)", "parameters": [ { "description": null, "name": "argument", "optional": false, "repeats": false } ], "trailing_repeats": false }, "sources": { "metadata": { "admission": { "label": "implemented", "reason": null }, "arity": { "max": 1, "min": 1 }, "category": "Information functions", "classification": { "arg_preparation_profile": "ValuesOnlyPreAdapter", "coercion_lift_profile": "Custom", "determinism_class": "Deterministic", "error_collapse_profile": "None", "fec_dependency_profile": "None", "host_interaction_class": "None", "kernel_signature_class": "Custom", "rich_value_usage": "RichBlind", "surface_fec_dependency_profile": "RefOnly", "thread_safety_class": "SafePure", "volatility_class": "NonVolatile" }, "descriptions": { "long": null, "short": "TRUE when a LAMBDA parameter was left out of the call", "short_source": "dna-calc-own" }, "docs": { "english_description": "Checks whether the value in a LAMBDA is missing and returns TRUE or FALSE", "microsoft_url": "https://support.microsoft.com/en-us/office/isomitted-function-831d6fbc-0f07-40c4-9c5b-9c73fd1d60c1" }, "entry_kind": "built_in_function", "localized_family_names": null, "localized_names": [ { "locale": "ar-SA", "name": "ISOMITTED" }, { "locale": "bg-BG", "name": "ISOMITTED" }, { "locale": "cs-CZ", "name": "ISOMITTED" }, { "locale": "da-DK", "name": "ISOMITTED" }, { "locale": "de-DE", "name": "ISOMITTED" }, { "locale": "el-GR", "name": "ISOMITTED" }, { "locale": "en-AU", "name": "ISOMITTED" }, { "locale": "en-GB", "name": "ISOMITTED" }, { "locale": "en-US", "name": "ISOMITTED" }, { "locale": "es-ES", "name": "ISOMITTED" }, { "locale": "et-EE", "name": "ISOMITTED" }, { "locale": "fi-FI", "name": "ISOMITTED" }, { "locale": "fr-FR", "name": "ISOMITTED*" }, { "locale": "he-IL", "name": "ISOMITTED" }, { "locale": "hr-HR", "name": "ISOMITTED" }, { "locale": "hu-HU", "name": "ISOMITTED" }, { "locale": "id-ID", "name": "ISOMITTED" }, { "locale": "it-IT", "name": "ISOMITTED" }, { "locale": "ja-JP", "name": "ISOMITTED" }, { "locale": "ko-KR", "name": "ISOMITTED" }, { "locale": "lt-LT", "name": "ISOMITTED" }, { "locale": "lv-LV", "name": "ISOMITTED" }, { "locale": "nb-NO", "name": "ISOMITTED" }, { "locale": "nl-NL", "name": "ISOMITTED" }, { "locale": "pl-PL", "name": "ISOMITTED" }, { "locale": "pt-BR", "name": "ISOMITTED" }, { "locale": "pt-PT", "name": "ISOMITTED" }, { "locale": "ro-RO", "name": "ISOMITTED" }, { "locale": "ru-RU", "name": "ПРОПУЩЕНО" }, { "locale": "sk-SK", "name": "ISOMITTED" }, { "locale": "sl-SI", "name": "ISOMITTED" }, { "locale": "sr-Latn-RS", "name": "ISOMITTED" }, { "locale": "sv-SE", "name": "ÄRUTELÄMNAT" }, { "locale": "th-TH", "name": "ISOMITTED" }, { "locale": "tr-TR", "name": "ATLANMIŞ" }, { "locale": "uk-UA", "name": "ISOMITTED" }, { "locale": "vi-VN", "name": "ISOMITTED" }, { "locale": "zh-CN", "name": "ISOMITTED" }, { "locale": "zh-HK", "name": "ISOMITTED" }, { "locale": "zh-TW", "name": "ISOMITTED" } ], "signature": { "display": "ISOMITTED(argument)", "parameters": [ { "description": null, "name": "argument", "optional": false, "repeats": false } ], "trailing_repeats": false }, "surface_name": "ISOMITTED", "version_marker": null, "xlcall": null }, "microsoft": "https://support.microsoft.com/en-us/office/isomitted-function-831d6fbc-0f07-40c4-9c5b-9c73fd1d60c1" }, "try_it": { "formula": "=ISOMITTED(1)" }, "url": "https://handbook.dnacalc.com/functions/ISOMITTED.html", "variants": [], "versions": [] }