"existential type" meaning in English

{
  "forms": [
    {
      "form": "existential types",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "existential type (plural existential types)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Programming",
          "orig": "en:Programming",
          "parents": [
            "Computing",
            "Software engineering",
            "Technology",
            "Computer science",
            "Engineering",
            "Software",
            "All topics",
            "Sciences",
            "Applied sciences",
            "Media",
            "Fundamental",
            "Communication"
          ],
          "source": "w"
        },
        {
          "_dis": "66 34",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "ref": "2002, Benjamin C. Pierce, Types and Programming Languages, MIT Press, page 363",
          "text": "Existential types are fundamentally no more complicated than universal types (in fact, we will see in §24.3 that existentials can straightforwardly be encoded in terms of universals).",
          "type": "quotation"
        },
        {
          "ref": "2021, Dean Wampler, chapter 16, in Programming Scala, 3rd edition, O'Reilly",
          "text": "Scala 2 supported existential types, a way of abstracting over types. They let you assert that some type exists without specifying exactly what it is, usually because you don't know what it is and you don't need to know it in the current context.",
          "type": "quotation"
        },
        {
          "ref": "2021, Jon Gjengset, Rust for Rustaceans, No Starch Press, page 34",
          "text": "This behavior is what gives existential types their name: we are asserting that there exists some concrete type that matches the signature, and we leave it up to the compiler to find what that type is.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A type that hides the underlying concrete type(s)."
      ],
      "id": "en-existential_type-en-noun-Q4UGcc9t",
      "links": [
        [
          "programming",
          "programming#Noun"
        ],
        [
          "type system",
          "type system"
        ],
        [
          "type",
          "type"
        ],
        [
          "concrete",
          "concrete"
        ]
      ],
      "qualifier": "type systems",
      "raw_glosses": [
        "(programming, type systems) A type that hides the underlying concrete type(s)."
      ],
      "synonyms": [
        {
          "word": "existential"
        }
      ],
      "topics": [
        "computing",
        "engineering",
        "mathematics",
        "natural-sciences",
        "physical-sciences",
        "programming",
        "sciences"
      ]
    },
    {
      "categories": [],
      "examples": [
        {
          "ref": "2001, John F. Schumaker, The Age of Insanity: Modernity and Mental Health, Greenwood Publishing Group, →LCCN, →OCLC, page 122",
          "text": "This is an existential type of anxiety that stems from the feeling that we are not at home in this world.",
          "type": "quotation"
        },
        {
          "ref": "2007 November 26, Paul Ferrara, Flash of Eden, AuthorHouse, →LCCN, →OCLC, page 120",
          "text": "He was an existential type dude with no belongings to speak of. He didn't care about tomorrow; he lived in the moment. He was always reading a book; quiet yet explosive.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Used other than figuratively or idiomatically: see existential, type."
      ],
      "id": "en-existential_type-en-noun-S7Hgj~mn",
      "links": [
        [
          "existential",
          "existential#English"
        ],
        [
          "type",
          "type#English"
        ]
      ]
    }
  ],
  "word": "existential type"
}

{
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English multiword terms",
    "English nouns"
  ],
  "forms": [
    {
      "form": "existential types",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "existential type (plural existential types)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English terms with quotations",
        "en:Programming"
      ],
      "examples": [
        {
          "ref": "2002, Benjamin C. Pierce, Types and Programming Languages, MIT Press, page 363",
          "text": "Existential types are fundamentally no more complicated than universal types (in fact, we will see in §24.3 that existentials can straightforwardly be encoded in terms of universals).",
          "type": "quotation"
        },
        {
          "ref": "2021, Dean Wampler, chapter 16, in Programming Scala, 3rd edition, O'Reilly",
          "text": "Scala 2 supported existential types, a way of abstracting over types. They let you assert that some type exists without specifying exactly what it is, usually because you don't know what it is and you don't need to know it in the current context.",
          "type": "quotation"
        },
        {
          "ref": "2021, Jon Gjengset, Rust for Rustaceans, No Starch Press, page 34",
          "text": "This behavior is what gives existential types their name: we are asserting that there exists some concrete type that matches the signature, and we leave it up to the compiler to find what that type is.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A type that hides the underlying concrete type(s)."
      ],
      "links": [
        [
          "programming",
          "programming#Noun"
        ],
        [
          "type system",
          "type system"
        ],
        [
          "type",
          "type"
        ],
        [
          "concrete",
          "concrete"
        ]
      ],
      "qualifier": "type systems",
      "raw_glosses": [
        "(programming, type systems) A type that hides the underlying concrete type(s)."
      ],
      "synonyms": [
        {
          "word": "existential"
        }
      ],
      "topics": [
        "computing",
        "engineering",
        "mathematics",
        "natural-sciences",
        "physical-sciences",
        "programming",
        "sciences"
      ]
    },
    {
      "categories": [
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2001, John F. Schumaker, The Age of Insanity: Modernity and Mental Health, Greenwood Publishing Group, →LCCN, →OCLC, page 122",
          "text": "This is an existential type of anxiety that stems from the feeling that we are not at home in this world.",
          "type": "quotation"
        },
        {
          "ref": "2007 November 26, Paul Ferrara, Flash of Eden, AuthorHouse, →LCCN, →OCLC, page 120",
          "text": "He was an existential type dude with no belongings to speak of. He didn't care about tomorrow; he lived in the moment. He was always reading a book; quiet yet explosive.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Used other than figuratively or idiomatically: see existential, type."
      ],
      "links": [
        [
          "existential",
          "existential#English"
        ],
        [
          "type",
          "type#English"
        ]
      ]
    }
  ],
  "word": "existential type"
}