Commit 8147abe1 authored by Adithya C. Ganesh's avatar Adithya C. Ganesh 💬

Add starter code

parent bd9065fd
Pipeline #45385074 passed with stages
in 5 minutes and 12 seconds
---
title: Assignment 3
---
The `Functor` is the most fundamental typeclass in the standard libraries. Intuitively, a `Functor` can be viewed as a sort of "container," coupled with an ability to apply a function to every element in the container.
It is defined as follows, where the `fmap` function generalizes the `map` function.
......@@ -7,18 +11,19 @@ class Functor f where
fmap :: (a -> b) -> f a -> f b
```
1. The `Either` type represents values with two possibilities: a value of type `Either a b` is either `Left a` or `Right b`.
### Problem 1
The `Either` type represents values with two possibilities: a value of type `Either a b` is either `Left a` or `Right b`. By convention, the `Left` constructor is used to hold an error value and the `Right` constructor is used to hold a correct value.
```haskell
data Either a b = Left a | Right b
```
By convention, the `Left` constructor is used to hold an error value and the `Right` constructor is used to hold a correct value.
Define an instance of `Functor` for `Either e` for a fixed `e`.
2. The `Data.Tree` module implements a rose tree - also, a multiway tree - as follows.
### Problem 2
We can implement a rose tree - also, a multiway tree - as follows. The `Data.Tree` module has an implementation; one possible implementation is as follows:
```haskell
data Tree a = Node a [Tree a]
......@@ -26,8 +31,8 @@ data Tree a = Node a [Tree a]
Define an instance of `Functor` for this datatype.
3. Is this statement true or false?
### Problem 3
The composition of two `Functor`s is also a `Functor`.
Is this statement true or false? The composition of two `Functor`s is also a `Functor`.
If false, give a counterexample; if true, provide an explanation (ideally with some code).
\ No newline at end of file
If false, give a counterexample; if true, provide an explanation.
Copyright Author name here (c) 2019
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of Author name here nor the names of other
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
import Distribution.Simple
main = defaultMain
name: assignment3
version: 0.1.0.0
-- synopsis:
-- description:
homepage: https://github.com/githubuser/assignment3#readme
license: BSD3
license-file: LICENSE
author: Author name here
maintainer: example@example.com
copyright: 2019 Author name here
category: Web
build-type: Simple
cabal-version: >=1.10
extra-source-files: README.md
executable assignment3
hs-source-dirs: src
main-is: Main.hs
default-language: Haskell2010
build-depends: base >= 4.7 && < 5
module Main where
main :: IO ()
main = do
putStrLn "hello world"
-- Problem 1 --
-- MyEither used to distinguish from Prelude.Either
data MyEither a b = Left a | Right b
instance Functor (MyEither a) where
fmap = undefined -- Implementation here
-- Problem 2 --
data Tree a = Node a [Tree a]
instance Functor Tree where
fmap = undefined -- Implementation here
# This file was automatically generated by 'stack init'
#
# Some commonly used options have been documented as comments in this file.
# For advanced use and comprehensive documentation of the format, please see:
# https://docs.haskellstack.org/en/stable/yaml_configuration/
# Resolver to choose a 'specific' stackage snapshot or a compiler version.
# A snapshot resolver dictates the compiler version and the set of packages
# to be used for project dependencies. For example:
#
# resolver: lts-3.5
# resolver: nightly-2015-09-21
# resolver: ghc-7.10.2
#
# The location of a snapshot can be provided as a file or url. Stack assumes
# a snapshot provided as a file might change, whereas a url resource does not.
#
# resolver: ./custom-snapshot.yaml
# resolver: https://example.com/snapshots/2018-01-01.yaml
resolver: lts-13.5
# User packages to be built.
# Various formats can be used as shown in the example below.
#
# packages:
# - some-directory
# - https://example.com/foo/bar/baz-0.0.2.tar.gz
# - location:
# git: https://github.com/commercialhaskell/stack.git
# commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
# subdirs:
# - auto-update
# - wai
packages:
- .
# Dependency packages to be pulled from upstream that are not in the resolver
# using the same syntax as the packages field.
# (e.g., acme-missiles-0.3)
# extra-deps: []
# Override default flag values for local packages and extra-deps
# flags: {}
# Extra package databases containing global packages
# extra-package-dbs: []
# Control whether we use the GHC we find on the path
# system-ghc: true
#
# Require a specific version of stack, using version ranges
# require-stack-version: -any # Default
# require-stack-version: ">=1.9"
#
# Override the architecture used by stack, especially useful on Windows
# arch: i386
# arch: x86_64
#
# Extra directories used by stack for building
# extra-include-dirs: [/path/to/dir]
# extra-lib-dirs: [/path/to/dir]
#
# Allow a newer minor version of GHC than the snapshot specifies
# compiler-check: newer-minor
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment