updates to cs194 + language overview

haskell/courses/upenn_cs194/week_1.page

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+---
+title: Week One Notes
+toc: no
+format: markdown
+...
+
+# Week One - Haskell Basics
+
+## What Is Haskell?
+
+  * Created in late 1980s by academics
+  * Functional
+  * Pure
+  * Lazy
+  * Statically Typed
+
+## Course Themes
+
+  * Types
+  * Abstraction
+  * Wholemeal Programming
+
+## Literate Haskell
+
+  * Only lines preceded by '>' are code
+  * All other lines are comments
+
+## Declarations of Variables
+
+~~~ {.haskell}
+x :: Int
+x = 3
+~~~
+
+  * Declares a variable `x` of type `Int`
+  * Defines the value of the variable `x` to be `3`
+  * `=` is *definition*, not *assignment*
+  * variables are just names for values
+
+## Basic Types
+
+  * `Int` - Machine-sized integers
+  * `Integer` - Arbitrary-precision integers
+  * `Double` - Double-precision floating point
+  * `Bool` - Booleans
+  * `Char` - Unicode characters
+  * `String` - Lists of characters with special syntax
+
+## GHCi
+
+  * A Haskell Read Eval Print Loop (REPL)
+  * `:load` - load a haskell file
+  * `:reload` - reload the file
+  * `:type` - return the type of an expression
+  * `:?` - give a list of commands
+
+## Arithmetic
+
+  * Infix operators, `+`, `-`, `*`, `\`, `^`
+  * Negation needs parens: `(-3)`
+  * `div` for integer division
+  * `mod` for integer remainder
+  * Backticks turn named functions to infix operators
+
+## Boolean Logic
+
+  *
+
+## Defining Basic Functions
+
+## Pairs
+
+## Using Functions, Multiple Arguments
+
+## Lists
+
+## Constructing Lists
+
+## Functions on Lists
+
+## Combining Functions
+
+## A Word About Error Messages

haskell/language.page

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+---
+title: Haskell Language
+toc: no
+format: markdown
+...
+
+Haskell is a programming language; a formal notation for describing
+computation. It can be described in terms of its [syntax]() and
+[semantics](). It is also often helpful to know about the [origins]()
+and [intuitions]() behind its concepts as well.
+
+It is one thing to know *about* a language, and quite another to know
+how to *use* it well. Learning to express ideas a language effectively
+involves the [pragmatics]() of the language.
+
+# Haskell Programs
+
+A program in Haskell is a collection of [modules](), including at
+least the `Main` module. Modules consist of [declarations](), which
+define elements of the program. The declarations contain
+[expressions](), which denote [values]() and have [types](). All of
+the above are built syntactically from the [lexical structure]() of
+text in files.
+
+# Haskell Tools
+
+Although Haskell is a useful language for communication of ideas about
+computation between humans, it also forms a practical language for
+executing programs on computers when coupled with [implementations]().