The Experts below are selected from a list of 9546 Experts worldwide ranked by ideXlab platform

James Noble - One of the best experts on this subject based on the ideXlab platform.

  • the billion dollar fix safe modular circular initialisation
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Initialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research languages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented languages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure Placeholders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

  • the billion dollar fix safe modular circular initialisation with Placeholders and Placeholder types
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Ini- tialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research lan- guages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented lan- guages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure place- holders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

Marco Servetto - One of the best experts on this subject based on the ideXlab platform.

  • the billion dollar fix safe modular circular initialisation
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Initialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research languages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented languages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure Placeholders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

  • the billion dollar fix safe modular circular initialisation with Placeholders and Placeholder types
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Ini- tialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research lan- guages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented lan- guages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure place- holders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

Julian Mackay - One of the best experts on this subject based on the ideXlab platform.

  • the billion dollar fix safe modular circular initialisation
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Initialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research languages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented languages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure Placeholders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

  • the billion dollar fix safe modular circular initialisation with Placeholders and Placeholder types
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Ini- tialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research lan- guages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented lan- guages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure place- holders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

Alex Potanin - One of the best experts on this subject based on the ideXlab platform.

  • the billion dollar fix safe modular circular initialisation
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Initialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research languages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented languages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure Placeholders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

  • the billion dollar fix safe modular circular initialisation with Placeholders and Placeholder types
    European Conference on Object-Oriented Programming, 2013
    Co-Authors: Marco Servetto, Julian Mackay, Alex Potanin, James Noble
    Abstract:

    Programmers often need to initialise circular structures of objects. Ini- tialisation should be safe (so that programs can never suffer null pointer exceptions or otherwise observe uninitialised values) and modular (so that each part of the circular structure can be written and compiled separately). Unfortunately, existing languages do not support modular circular initialisation: programmers in practical languages resort to Tony Hoare's "Billion Dollar Mistake": initialising variables with nulls, and then hoping to fix them up afterward. While recent research lan- guages have offered some solutions, none fully support safe modular circular initialisation. We present Placeholders, a straightforward extension to object-oriented lan- guages that describes circular structures simply, directly, and modularly. In typed languages, Placeholders can be described by Placeholder types that ensure place- holders are used safely. We define an operational semantics for Placeholders, a type system for Placeholder types, and prove soundness. Incorporating Placeholders into object-oriented languages should make programs simultaneously simpler to write, and easier to write correctly.

Bradley R Cairns - One of the best experts on this subject based on the ideXlab platform.

  • Placeholder nucleosomes underlie germline to embryo dna methylation reprogramming
    Cell, 2018
    Co-Authors: Patrick J Murphy, Shan Fu Wu, Cody R James, Candice L Wike, Bradley R Cairns
    Abstract:

    Summary The fate and function of epigenetic marks during the germline-to-embryo transition is a key issue in developmental biology, with relevance to stem cell programming and transgenerational inheritance. In zebrafish, DNA methylation patterns are programmed in transcriptionally quiescent cleavage embryos; paternally inherited patterns are maintained, whereas maternal patterns are reprogrammed to match the paternal. Here, we provide the mechanism by demonstrating that "Placeholder" nucleosomes, containing histone H2A variant H2A.Z(FV) and H3K4me1, virtually occupy all regions lacking DNA methylation in both sperm and cleavage embryos and reside at promoters encoding housekeeping and early embryonic transcription factors. Upon genome-wide transcriptional onset, genes with Placeholder become either active (H3K4me3) or silent (H3K4me3/K27me3). Notably, perturbations causing Placeholder loss confer DNA methylation accumulation, whereas acquisition/expansion of Placeholder confers DNA hypomethylation and improper gene activation. Thus, during transcriptionally quiescent gametic and embryonic stages, an H2A.Z(FV)/H3K4me1-containing Placeholder nucleosome deters DNA methylation, poising parental genes for either gene-specific activation or facultative repression.

  • Placeholder nucleosomes underlie germline to embryo dna methylation reprogramming
    bioRxiv, 2017
    Co-Authors: Patrick J Murphy, Shan Fu Wu, Cody R James, Candice L Wike, Bradley R Cairns
    Abstract:

    The fate and function of epigenetic marks during the germline-to-embryo transition is a key issue in developmental biology, with relevance to stem cell programming and trans-generational inheritance. In zebrafish, DNA methylation (DNAme) patterns are programmed in transcriptionally-quiescent cleavage embryos; remarkably, paternally-inherited patterns are maintained, whereas maternal patterns are reprogrammed to match the paternal. Here we provide the mechanism, by demonstrating that 9Placeholder9 nucleosomes, containing histone H2A variant H2A.Z(FV) and H3K4me1, occupy virtually all regions lacking DNAme in both sperm and cleavage embryos, and resides at promoters encoding housekeeping and early embryonic transcription factors. Upon genome-wide transcriptional onset, genes with Placeholder become either active (H3K4me3) or silent (H3K4me3/K27me3). Importantly, functional perturbation causing Placeholder loss confers DNAme accumulation, whereas acquisition/expansion of Placeholder confers DNA hypomethylation and improper gene activation. Thus, during transcriptionally-quiescent gametic and embryonic stages, an H2A.Z(FV)/H3K4me1-containing Placeholder nucleosome deters DNAme, poising parental genes for either gene-specific activation or facultative repression.