sdiehl/write-you-a-haskell
1
1
Fork 0
mirror of https://github.com/sdiehl/write-you-a-haskell.git synced 2024-08-16 23:20:54 +03:00
Code Issues Projects Releases Wiki Activity

Merge pull request #66 from yupferris/master

Browse Source 
Small fixes in the Introduction chapter
This commit is contained in:
Stephen Diehl 2015-05-17 11:10:03 -04:00
commit 169b738671
2 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
000_introduction.md
View File

@ -109,13 +109,13 @@ one element of a set to each element in another set. If a function $f(x) = a$
then the function evaluated at $x$ will always have the value $a$. Central to
the notion of all mathematics is the notion of *equational reasoning*, where
if $a= f(x)$ then for an expression $g(f(x), f(x))$, this is always equivalent
to $g(a, a)$. In other words the values computed by functions can always be
to $g(a, a)$. In other words, the values computed by functions can always be
substituted freely at all occurrences.
The central idea of *functional programming* is to structure our programs in
such a way that we can reason about them as a system of equations just like
we can in mathematics. The evaluation of a pure function is one in which *side
effects* are prohibited, a function may only return a result without altering
effects* are prohibited; a function may only return a result without altering
the world in any *observable* way.
The implementation may perform effects, but central to this definition is the
@ -245,7 +245,7 @@ Parsing
The source code is simply the raw sequence of text that specifies the program.
Lexing splits the text stream into a sequence of *tokens*. Only the presence of
invalid symbols is checked, programs that are meaningless in other ways are
invalid symbols is checked; programs that are meaningless in other ways are
accepted.
Whitespace is either ignored or represented as a unique token in the stream.
@ -268,9 +268,9 @@ following:
]
```
We can then scan the token stream via and dispatch on predefined patterns of
tokens called *productions* and recursively builds up the syntax datatype for
the *abstract syntax tree* (AST) by traversal of the input stream.
We can then scan the token stream via dispatch on predefined patterns of
tokens called *productions*, and recursively build up the syntax datatype for
the *abstract syntax tree* (AST).
```haskell
type Name = String

1
CONTRIBUTORS.md
View File

@ -14,3 +14,4 @@ Contributors
* Dmitry Ivanov
* Christian Sievers
* Franklin Chen
* Jake Taylor