The infix vocabulary implements support for infix notation in Factor source code.

The usual infix math operators are supported:

The standard precedence rules apply: Grouping with parentheses before *, / and % before + and -.

You can call Factor words in infix expressions just as you would in C. There are some restrictions on which words are legal to use though:

You can access sequences inside infix expressions with the familiar seq[index] notation.

You can create sub- sequences inside infix expressions using seq[from:to] notation.

Additionally, you can step through sequences with seq[from:to:step] notation.

[infix

INFIX::

The usual infix math operators are supported:

• | + |

• | - |

• | * |

• | / |

• | **, which is the infix operator for ^. |

• | %, which is the infix operator for mod. |

The standard precedence rules apply: Grouping with parentheses before *, / and % before + and -.

USE: infix
[infix 5-40/10*2 infix] .

-3

-3

You can call Factor words in infix expressions just as you would in C. There are some restrictions on which words are legal to use though:

• | The word must return exactly one value. |

• | The word name must consist of the letters a-z, A-Z, _ or 0-9, and the first character can't be a number. |

USING: infix locals math.functions ;
:: binary_entropy ( p -- h )
[infix -(p*log(p) + (1-p)*log(1-p)) / log(2) infix] ;
[infix binary_entropy( sqrt(0.25) ) infix] .

1.0

1.0

You can access sequences inside infix expressions with the familiar seq[index] notation.

USING: arrays locals infix ;
[let { 1 2 3 4 } :> myarr [infix myarr[4/2]*3 infix] ] .

9

9

You can create sub- sequences inside infix expressions using seq[from:to] notation.

USING: arrays locals infix ;
[let "foobar" :> s [infix s[0:3] infix] ] .

"foo"

"foo"

Additionally, you can step through sequences with seq[from:to:step] notation.

USING: arrays locals infix ;
[let "reverse" :> s [infix s[::-1] infix] ] .

"esrever"

"esrever"

USING: arrays locals infix ;
[let "0123456789" :> s [infix s[::2] infix] ] .

"02468"

"02468"

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image. If you want, you can also
browse the documentation from within the UI developer tools. See
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for more information.

Factor 0.99 x86.64 (2173, heads/master-f3ee5c5979, Sep 18 2022 13:17:51)