This document discusses state monads in Haskell. It defines the State monad and its operators (>>=) and return. It shows how state is threaded through computations using these operators. It provides examples of using the state monad to increment a counter and to define functions like put and get that set and get the current state. In summary:
1) It introduces the State monad and its operators for threading state through computations.
2) It gives examples like incrementing a counter to demonstrate how the state is transformed and passed between function applications in the monad.
3) It shows how functions like put and get can be defined to set and access the internal state using the monad operators.
Math::Category is a Perl module that defines categories and mathematical structures like functors, natural transformations, and monads. It implements categories as objects with morphisms that have source and target objects. Functors map objects and morphisms between categories while natural transformations transform functors. The module also defines monads as endofunctors with additional structure and provides examples like the list and state monads. Kleisli categories are constructed from monads to model computations.
This document summarizes the similarities between State and other monadic types in Haskell like Maybe and IO. It shows that State, like these other types, forms a Kleisli triple with return and (>>=) (bind) operations. It provides examples of how return and (>>=) work for State, and explains that State is an instance of the Monad typeclass because it implements these functions in a way that satisfies the monad laws, making it a monad.
This document discusses state monads in Haskell. It defines the State monad and its operators (>>=) and return. It shows how state is threaded through computations using these operators. It provides examples of using the state monad to increment a counter and to define functions like put and get that set and get the current state. In summary:
1) It introduces the State monad and its operators for threading state through computations.
2) It gives examples like incrementing a counter to demonstrate how the state is transformed and passed between function applications in the monad.
3) It shows how functions like put and get can be defined to set and access the internal state using the monad operators.
Math::Category is a Perl module that defines categories and mathematical structures like functors, natural transformations, and monads. It implements categories as objects with morphisms that have source and target objects. Functors map objects and morphisms between categories while natural transformations transform functors. The module also defines monads as endofunctors with additional structure and provides examples like the list and state monads. Kleisli categories are constructed from monads to model computations.
This document summarizes the similarities between State and other monadic types in Haskell like Maybe and IO. It shows that State, like these other types, forms a Kleisli triple with return and (>>=) (bind) operations. It provides examples of how return and (>>=) work for State, and explains that State is an instance of the Monad typeclass because it implements these functions in a way that satisfies the monad laws, making it a monad.
1) A reporter hears that a lady named "Fukashigi" is in trouble, unable to solve a combinatorial problem involving counting paths on a grid.
2) The reporter implements an algorithm called Simpath in Perl to efficiently count the number of paths and solves a 9x9 grid problem in seconds, over 1 million times faster than brute force.
3) By using techniques like binary decision diagrams and sharing computation between identical subproblems, the algorithm is able to compress the exponential search space into a polynomial solution. This demonstrates the importance of algorithms for tackling combinatorial explosion.
The document discusses traits in object-oriented programming. Traits are similar to mixins and allow the aggregation of methods and properties. The document explains how traits work in various programming languages like Perl, Ruby, Java and describes operations like trait summation, aliasing and exclusion. Trait systems allow flexible composition of behaviors while avoiding problems of multiple inheritance.
This document discusses monads in Perl and provides examples using the List and AnyEvent monads. It explains that monads consist of a type, unit and flat_map functions. The List monad is implemented with arrays as the type and unit/flat_map functions are defined. AnyEvent uses condvar objects as values that require callbacks to access results, demonstrating how monads allow sequential processing of asynchronous code.
The document discusses type systems and type inference in Perl. It explains that in Perl, what matters is whether a term is "typeable" rather than its specific type. Terms are typeable if they can be evaluated in the same way as in the typed lambda calculus. The document then covers type inference algorithms for Perl, including typed lambda calculus, building and solving equations to infer types, polymorphic types, record types, subtyping, and recursive types.
1) The document presents a mathematical proof using pullbacks and mono morphisms.
2) It proves that if f'k1 = f'k2 then g'k1 = g'k2, where k1 and k2 are mono morphisms.
3) The proof proceeds over 9 steps, applying properties of pullbacks and mono morphisms to deduce the conclusion.
Git is a distributed version control system invented by Linus Torvalds that stores data in a file system made up of snapshots of a project over time. It allows developers to work collaboratively by tracking changes to files and coordinating code changes between team members or branches of development. Git uses a client-server model with local repositories that can be pushed to and pulled from remote repositories hosted on services like GitHub.
This document discusses state monads in Haskell. It explains that a state monad maintains internal state and allows functions to access and modify that state. Functions in a state monad return both a value and the new state. The document provides examples of using state monads to model counters, character sequences, and state transitions. It shows how the state is threaded through function applications using the (>>=) operator.
The document discusses generating documentation from POD files using various Perl modules. It shows commands to:
1) Convert a POD file to HTML using pod2html and encounters an unknown directive error.
2) Batch convert all POD files in a lib directory to HTML using Pod::Simple::HTMLBatch.
3) Configure Pod::Simple::HTMLBatch to use the Pod::Simple::XHTML renderer.
4) Generate documentation projects from POD files using pod2projdocs.
5) Create a Pod site from lib POD files using podsite.
This document discusses uWSGI, an application server gateway interface that can host WSGI applications written in languages like Python, Lua, Perl, Ruby, Erlang, and JVM/mono. It is non-blocking and fast, using techniques like fibers in Ruby and coroutines in other languages. It also has features like a fast router and ability to subscribe to events. uWSGI can host PSGI applications and is lightweight enough to be used with libraries like AnyEvent on platforms like OS X and dotcloud.
This document discusses arrows in Perl. It describes how arrows generalize monads by allowing composition of functions with arbitrary signatures. It provides examples of implementing arrow classes in Perl, including using subroutines as arrows and implementing arrow operators like first, split, and parallel composition. It also discusses how arrows form a premonoidal category and relates arrows to monads.
This document discusses AnyEvent, a module for asynchronous programming in Perl using non-blocking I/O. It provides an overview of how AnyEvent works and can be used to build event-driven applications. The document also covers Plack and PSGI, describing them as standards for building web applications in Perl using a common interface that can run on different web servers via middleware like Plack.
The document discusses various techniques in Perl for dealing with reference cycles and memory leaks caused by strong references, including using weak references, extracting needed data from objects before destroying them, and passing objects into subroutines to avoid capturing them. It also discusses analogous techniques used in Objective-C like weak references and guard objects to break cycles.
An introduction of Levenshtein Automata to implement fuzzy search with common RDBMSs.
The original of blog entry is here;
http://blog.notdot.net/2010/07/Damn-Cool-Algorithms-Levenshtein-Automata
This document introduces monads for programmers who are familiar with lambdas. It uses a bank API example to demonstrate how monads can be used to compose functions in a cleaner way that avoids null pointer exceptions. The code is refactored using a bind function to chain the API calls together in a way that looks like the business logic. This introduces the reader to how monads can increase modularity and manage complexity in large codebases.
1) A reporter hears that a lady named "Fukashigi" is in trouble, unable to solve a combinatorial problem involving counting paths on a grid.
2) The reporter implements an algorithm called Simpath in Perl to efficiently count the number of paths and solves a 9x9 grid problem in seconds, over 1 million times faster than brute force.
3) By using techniques like binary decision diagrams and sharing computation between identical subproblems, the algorithm is able to compress the exponential search space into a polynomial solution. This demonstrates the importance of algorithms for tackling combinatorial explosion.
The document discusses traits in object-oriented programming. Traits are similar to mixins and allow the aggregation of methods and properties. The document explains how traits work in various programming languages like Perl, Ruby, Java and describes operations like trait summation, aliasing and exclusion. Trait systems allow flexible composition of behaviors while avoiding problems of multiple inheritance.
This document discusses monads in Perl and provides examples using the List and AnyEvent monads. It explains that monads consist of a type, unit and flat_map functions. The List monad is implemented with arrays as the type and unit/flat_map functions are defined. AnyEvent uses condvar objects as values that require callbacks to access results, demonstrating how monads allow sequential processing of asynchronous code.
The document discusses type systems and type inference in Perl. It explains that in Perl, what matters is whether a term is "typeable" rather than its specific type. Terms are typeable if they can be evaluated in the same way as in the typed lambda calculus. The document then covers type inference algorithms for Perl, including typed lambda calculus, building and solving equations to infer types, polymorphic types, record types, subtyping, and recursive types.
1) The document presents a mathematical proof using pullbacks and mono morphisms.
2) It proves that if f'k1 = f'k2 then g'k1 = g'k2, where k1 and k2 are mono morphisms.
3) The proof proceeds over 9 steps, applying properties of pullbacks and mono morphisms to deduce the conclusion.
Git is a distributed version control system invented by Linus Torvalds that stores data in a file system made up of snapshots of a project over time. It allows developers to work collaboratively by tracking changes to files and coordinating code changes between team members or branches of development. Git uses a client-server model with local repositories that can be pushed to and pulled from remote repositories hosted on services like GitHub.
This document discusses state monads in Haskell. It explains that a state monad maintains internal state and allows functions to access and modify that state. Functions in a state monad return both a value and the new state. The document provides examples of using state monads to model counters, character sequences, and state transitions. It shows how the state is threaded through function applications using the (>>=) operator.
The document discusses generating documentation from POD files using various Perl modules. It shows commands to:
1) Convert a POD file to HTML using pod2html and encounters an unknown directive error.
2) Batch convert all POD files in a lib directory to HTML using Pod::Simple::HTMLBatch.
3) Configure Pod::Simple::HTMLBatch to use the Pod::Simple::XHTML renderer.
4) Generate documentation projects from POD files using pod2projdocs.
5) Create a Pod site from lib POD files using podsite.
This document discusses uWSGI, an application server gateway interface that can host WSGI applications written in languages like Python, Lua, Perl, Ruby, Erlang, and JVM/mono. It is non-blocking and fast, using techniques like fibers in Ruby and coroutines in other languages. It also has features like a fast router and ability to subscribe to events. uWSGI can host PSGI applications and is lightweight enough to be used with libraries like AnyEvent on platforms like OS X and dotcloud.
This document discusses arrows in Perl. It describes how arrows generalize monads by allowing composition of functions with arbitrary signatures. It provides examples of implementing arrow classes in Perl, including using subroutines as arrows and implementing arrow operators like first, split, and parallel composition. It also discusses how arrows form a premonoidal category and relates arrows to monads.
This document discusses AnyEvent, a module for asynchronous programming in Perl using non-blocking I/O. It provides an overview of how AnyEvent works and can be used to build event-driven applications. The document also covers Plack and PSGI, describing them as standards for building web applications in Perl using a common interface that can run on different web servers via middleware like Plack.
The document discusses various techniques in Perl for dealing with reference cycles and memory leaks caused by strong references, including using weak references, extracting needed data from objects before destroying them, and passing objects into subroutines to avoid capturing them. It also discusses analogous techniques used in Objective-C like weak references and guard objects to break cycles.
An introduction of Levenshtein Automata to implement fuzzy search with common RDBMSs.
The original of blog entry is here;
http://blog.notdot.net/2010/07/Damn-Cool-Algorithms-Levenshtein-Automata
This document introduces monads for programmers who are familiar with lambdas. It uses a bank API example to demonstrate how monads can be used to compose functions in a cleaner way that avoids null pointer exceptions. The code is refactored using a bind function to chain the API calls together in a way that looks like the business logic. This introduces the reader to how monads can increase modularity and manage complexity in large codebases.
