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#Haskell tutorial install
#Haskell tutorial code
#Haskell tutorial free

The : operator appends an item to the beginning of a list. Lists are used to hold multiple values of the same type. You can return () from an I/O action if you don't want to return anything.īasic data types can be easily combined in two ways: lists, which go in, and tuples, which go in (parentheses). You can think of this as similar to the void keyword in C family languages.

The final type worth mentioning here is (), pronounced "unit." It only has one value, also written as () and pronounced "unit." The first two are instances of Integral, and the last three are instances of Fractional.

Rational is a fraction type, with no rounding error.Īll five are instances of the Num type class.

Double is a double precision floating point number.

Float is a single precision floating point number.

Integer is an integer with unlimited precision.

Int is an integer with at least 30 bits of precision.

There are five numeric types in the Haskell "prelude" (the part of the library you get without having to import anything):

gcd 15 20 (which is a function call, incidentally) can be any integral type, but not a fractional type.

42.0 can be any fractional type, but not an integral type.

(This is why I was able to declare 5 as either an Int or a Double earlier.) These types use "type classes." They mean: (In case you noticed, is another way of saying String. This is useful because you don't generally have to declare your types. You can also ask ghci what type it has chosen for something. This is a rule of the language, not a naming convention. Variables always start with lower-case letters. Types (and type classes, discussed later) always start with upper-case letters in Haskell. Main = do putStrLn "What is 2 + 2?" x 5 :: Int This doesn't work so well in ghci, but try putting the file in a source file (say, Test.hs) and build it. If you leave off the braces and semicolons, then indentation becomes significant. There is actually another way to write do blocks. I/O actions can be used to read from and write to the console. There are no parentheses as part of the function call: Strings are in "double quotes." You can concatenate them with ++.Ĭalling functions is done by putting the arguments directly after the function. You can type most math expressions directly into ghci and get an answer.

#Haskell tutorial code

The second is an interpreter that lets you write Haskell code and get feedback right away. The first compiles Haskell libraries or applications to binary code. Once you've installed GHC, you get two programs you're interested in right now: ghc, and ghci. GHC binaries are available for GNU/Linux, FreeBSD, MacOS, Windows, and Solaris. Its closest popular relative is probably the ML family of languages (which are not, however, lazy languages). Haskell is a functional (that is, everything is done with function calls), statically, implicitly typed ( types are checked by the compiler, but you don't have to declare them), lazy (nothing is done until it needs to be) language. 9 Topics that don't fit in 10 minute limit.A Gentle Introduction to Haskell (English, File:GentleFR.There are many good Haskell tutorials and books.

#Haskell tutorial install

If you encounter a Could not find module ‘Control.Parallel’ error, please install the parallel library with cabal install -lib parallel Where to go from here

A +RTS -N2 2.14s user 0.02s system 149% cpu 1.449 totalĬongratulations! You are now programming your multicore! Note that in versions of GHC prior to GHC 7, you can leave off the -rtsopts flagĪnd now we can run our multicore program. Import Control.Parallel main = a ` par ` b ` par ` c ` pseq ` print ( a + b + c ) where a = ack 3 10 b = fac 42 c = fib 34 fac 0 = 1 fac n = n * fac ( n - 1 ) ack 0 n = n + 1 ack m 0 = ack ( m - 1 ) 1 ack m n = ack ( m - 1 ) ( ack m ( n - 1 )) fib 0 = 0 fib 1 = 1 fib n = fib ( n - 1 ) + fib ( n - 2 )Ĭompiling with -threaded and optimizations on: Probably was "Hello, world!", so let's do that: If you've learned to program another language, your first program done.Īnd you are presented with a prompt. Alternatively, if you are on Windows, you may choose WinGHCi in the Start menu. If you have installed the Haskell Platform, open a terminal and type ghci (the name of the executable of the GHC interpreter) at the command prompt. Try Haskell provides a less complete but quicker way to give Haskell a shot.

#Haskell tutorial free

If you encounter difficulty, feel free to reach out to the Haskell community. The installation should be supported on most operating systems. The Platform comes with GHC, the de-facto standard Haskell compiler, and other tools that will help you program Haskell. The recommended way to get started with programming Haskell is the Haskell Platform. 4.1 Write your first parallel Haskell program.