#Programming_paradigms : #Functional programming
Seeks to use pure functions.
Pure functions:
• have no side effects
• return a value that depends only on their arguments. e.g.
• are easier to reason about and test.
• are more efficient. Once the function has been evaluated for an input, the result can be stored and referred to the next time the function of that input is needed, reducing the number of times the function is called. This is called #memoization.
• are less confusing to run in parallel (See #concurrent programming).
Using only pure functions complicates the otherwise simple task of IO since this appears to inherently require side effects.
Seeks to use pure functions.
Pure functions:
• have no side effects
• return a value that depends only on their arguments. e.g.
sin(x) will, for the same value of x, always return the same result.• are easier to reason about and test.
• are more efficient. Once the function has been evaluated for an input, the result can be stored and referred to the next time the function of that input is needed, reducing the number of times the function is called. This is called #memoization.
• are less confusing to run in parallel (See #concurrent programming).
Using only pure functions complicates the otherwise simple task of IO since this appears to inherently require side effects.
#language #Haskell
Haskell
First appeared: 1990
Features:
• Purely #functional
• Statically and strongly typed (#Static_typing, #Strong_typing)
• #Type_inferring
• Lazy (#Lazy_evaluation)
• #pattern_matching
• #list_comprehension
• Type classes and type polymorphism (#type_class)
• Concurrent (#concurrency)
• Monads
Monads
Monads are a general framework that can model different kinds of computation, including error handling, nondeterminism, parsing and software transactional memory. Monads are defined as ordinary datatypes, but Haskell provides some syntactic sugar for their use.
Glasgow Haskell Compiler
GHC or Glasgow Haskell Compiler is the most commonly-used Haskell compiler and the main implementation of Haskell. It is open source and provides a cross-platform environment for writing and testing. It supports numerous extensions, libraries, and optimisations that streamline the process of generating and executing code. GHC itself is written in Haskell (#Bootstrapping); but the runtime system which is essential to run programs is written in C and C--.
Front end: (lexer, parser and typechecker)
Preserves as much information about the source as possible until after type inference is complete, to provide clear error messages to users. After type checking, the code is desugared (#syntactic_sugar) into a typed, intermediate language known as "Core".
Simplifier or "middle end":
- is where most of the optimizations are performed as a series of source-to-source transformations in Core code.
Back end:
Transforms Core code into an internal representation of C--. The C-- code can then take one of three routes: it is either printed as C code for compilation with GCC, converted directly into native machine code, or converted to LLVM virtual machine code for compilation with LLVM. In all three cases, the resultant native code is finally linked against the GHC runtime system to produce an executable.
C--
C-- is a #C like programming language, designed to be generated by compilers for very high-level languages rather than written by human programmers. Unlike many other intermediate languages, its representation is plain #ASCII text, not bytecode or another binary format.
C-- is a "portable #assembly language", designed to ease the task of implementing a compiler which produces high quality #machine_code. This is done by having the compiler generate C-- code, delegating the harder work of low-level code generation and optimisation to a C-- compiler.
The C-- type system is deliberately designed to reflect constraints imposed by hardware rather than conventions imposed by higher-level languages. In C-- a value stored in a register or memory may have only one type: bit vector. However, bit vector is a polymorphic type and may come in several widths, e.g., bits8, bits32, or bits64. In addition to the bit-vector type C-- also provides a Boolean type bool, which can be computed by expressions and used for control flow but cannot be stored in a register or in memory. As in an assembly language, any higher type discipline, such as distinctions between signed, unsigned, float, and pointer, is imposed by the C-- operators or other syntactic constructs in the language.
Haskell
First appeared: 1990
Features:
• Purely #functional
• Statically and strongly typed (#Static_typing, #Strong_typing)
• #Type_inferring
• Lazy (#Lazy_evaluation)
• #pattern_matching
• #list_comprehension
• Type classes and type polymorphism (#type_class)
• Concurrent (#concurrency)
• Monads
Monads
Monads are a general framework that can model different kinds of computation, including error handling, nondeterminism, parsing and software transactional memory. Monads are defined as ordinary datatypes, but Haskell provides some syntactic sugar for their use.
Glasgow Haskell Compiler
GHC or Glasgow Haskell Compiler is the most commonly-used Haskell compiler and the main implementation of Haskell. It is open source and provides a cross-platform environment for writing and testing. It supports numerous extensions, libraries, and optimisations that streamline the process of generating and executing code. GHC itself is written in Haskell (#Bootstrapping); but the runtime system which is essential to run programs is written in C and C--.
Front end: (lexer, parser and typechecker)
Preserves as much information about the source as possible until after type inference is complete, to provide clear error messages to users. After type checking, the code is desugared (#syntactic_sugar) into a typed, intermediate language known as "Core".
Simplifier or "middle end":
- is where most of the optimizations are performed as a series of source-to-source transformations in Core code.
Back end:
Transforms Core code into an internal representation of C--. The C-- code can then take one of three routes: it is either printed as C code for compilation with GCC, converted directly into native machine code, or converted to LLVM virtual machine code for compilation with LLVM. In all three cases, the resultant native code is finally linked against the GHC runtime system to produce an executable.
C--
C-- is a #C like programming language, designed to be generated by compilers for very high-level languages rather than written by human programmers. Unlike many other intermediate languages, its representation is plain #ASCII text, not bytecode or another binary format.
C-- is a "portable #assembly language", designed to ease the task of implementing a compiler which produces high quality #machine_code. This is done by having the compiler generate C-- code, delegating the harder work of low-level code generation and optimisation to a C-- compiler.
The C-- type system is deliberately designed to reflect constraints imposed by hardware rather than conventions imposed by higher-level languages. In C-- a value stored in a register or memory may have only one type: bit vector. However, bit vector is a polymorphic type and may come in several widths, e.g., bits8, bits32, or bits64. In addition to the bit-vector type C-- also provides a Boolean type bool, which can be computed by expressions and used for control flow but cannot be stored in a register or in memory. As in an assembly language, any higher type discipline, such as distinctions between signed, unsigned, float, and pointer, is imposed by the C-- operators or other syntactic constructs in the language.
#language #D
D
- is a system programming language first appeared in 2001. Though it originated as a re-engineering of C++, D is a distinct language, having redesigned some core C++ features while also taking inspiration from other languages, notably Java, Python, Ruby, C#, and Eiffel.
D attempts to combine the performance and safety of compiled languages with the expressive power of modern dynamic languages. Idiomatic D code is commonly as fast as equivalent C++ code, while being shorter and memory-safe. Type inference, automatic memory management and syntactic sugar for common types allow faster development, while bounds checking, design by contract features and a concurrency-aware type system help reduce the occurrence of bugs.
Paradigms: #imperative, #object_oriented, #metaprogramming, #functional and #concurrent (actor model)
Comparison with C
Despite their difference, D has been constrained in its design by the rule that any code that is legal in both C and D should behave in the same way.
Comparison with C++
Things D gained before C++:
• closures
• anonymous functions
• compile time function execution
Things D adds:
• design by contract
• unit testing
• true modules
• garbage collection
• first class arrays
• associative arrays
• dynamic arrays
• array slicing
• nested functions
• lazy evaluation
• built-in support for documentation comments, allowing automatic documentation generation
Things D replaces:
• multiple inheritance is replaced by Java-style single inheritance with interfaces and mixins.
• template syntax is re-engineered
Things they have in common:
• D's declaration, statement and expression syntax closely matches that of C++.
• D retains C++'s ability to perform low-level coding and to add inline assembler. The inline assembler typifies the differences between D and application languages like Java and C#. An inline assembler lets programmers enter machine-specific assembly code within standard D code, a method often used by system programmers to access the low-level features of the processor needed to run programs that interface directly with the underlying hardware, such as operating systems and device drivers.
Docs: https://dlang.org/spec/spec.html
D
- is a system programming language first appeared in 2001. Though it originated as a re-engineering of C++, D is a distinct language, having redesigned some core C++ features while also taking inspiration from other languages, notably Java, Python, Ruby, C#, and Eiffel.
D attempts to combine the performance and safety of compiled languages with the expressive power of modern dynamic languages. Idiomatic D code is commonly as fast as equivalent C++ code, while being shorter and memory-safe. Type inference, automatic memory management and syntactic sugar for common types allow faster development, while bounds checking, design by contract features and a concurrency-aware type system help reduce the occurrence of bugs.
Paradigms: #imperative, #object_oriented, #metaprogramming, #functional and #concurrent (actor model)
Comparison with C
Despite their difference, D has been constrained in its design by the rule that any code that is legal in both C and D should behave in the same way.
Comparison with C++
Things D gained before C++:
• closures
• anonymous functions
• compile time function execution
Things D adds:
• design by contract
• unit testing
• true modules
• garbage collection
• first class arrays
• associative arrays
• dynamic arrays
• array slicing
• nested functions
• lazy evaluation
• built-in support for documentation comments, allowing automatic documentation generation
Things D replaces:
• multiple inheritance is replaced by Java-style single inheritance with interfaces and mixins.
• template syntax is re-engineered
Things they have in common:
• D's declaration, statement and expression syntax closely matches that of C++.
• D retains C++'s ability to perform low-level coding and to add inline assembler. The inline assembler typifies the differences between D and application languages like Java and C#. An inline assembler lets programmers enter machine-specific assembly code within standard D code, a method often used by system programmers to access the low-level features of the processor needed to run programs that interface directly with the underlying hardware, such as operating systems and device drivers.
Docs: https://dlang.org/spec/spec.html
SISAL
"Streams and Iteration in a Single Assignment Language" is a general-purpose single assignment functional programming language with strict semantics, implicit parallelism, and efficient array handling. It was derived from VAL (Value-oriented Algorithmic Language by Jack Dennis), and adds recursion and finite streams.
By: James McGraw
First appeared: 1983
First compiled implementation: 1986
Paradigms: #functional, #dataflow
Syntax: #Pascal -like
Performance: superior to #C and rivals #Fortran
SISAL is more than just a dataflow and fine-grain language; it is a set of tools that convert a textual human readable dataflow language into a graph format (named IF1 - Intermediary Form 1). Part of the SISAL project also involved converting this graph format into runable C code.
In 2010 SISAL saw a brief resurgence when a group of undergraduates at Worcester Polytechnic Institute investigated implementing a fine-grain parallelism backend for the SISAL language.
In 2018 SISAL got modernized with ident-based syntax, first-class functions, lambdas, closures and lazy semantics within project SISAL-IS.
#SISAL
"Streams and Iteration in a Single Assignment Language" is a general-purpose single assignment functional programming language with strict semantics, implicit parallelism, and efficient array handling. It was derived from VAL (Value-oriented Algorithmic Language by Jack Dennis), and adds recursion and finite streams.
By: James McGraw
First appeared: 1983
First compiled implementation: 1986
Paradigms: #functional, #dataflow
Syntax: #Pascal -like
Performance: superior to #C and rivals #Fortran
SISAL is more than just a dataflow and fine-grain language; it is a set of tools that convert a textual human readable dataflow language into a graph format (named IF1 - Intermediary Form 1). Part of the SISAL project also involved converting this graph format into runable C code.
In 2010 SISAL saw a brief resurgence when a group of undergraduates at Worcester Polytechnic Institute investigated implementing a fine-grain parallelism backend for the SISAL language.
In 2018 SISAL got modernized with ident-based syntax, first-class functions, lambdas, closures and lazy semantics within project SISAL-IS.
#SISAL